We use terraform in combination with localstack for testing purposes and recently there has been an update the the AWS terraform provider (https://github.com/terraform-providers/terraform-provider-aws/blob/master/CHANGELOG.md#2110-may-17-2019) that adds tag support to the SNS resource. Unforntunately the change to the terraform aws provider breaks compatibly with localstack as it now uses the ListTagsForResource API on SNS which localstack replies with a HTTP 500.

Here is the terraform debug output that shows the issue:
```
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: 2019/05/19 22:44:48 [DEBUG] [aws-sdk-go] DEBUG: Request sns/ListTagsForResource Details:                                                                                                                        
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: ---[ REQUEST POST-SIGN ]-----------------------------                                                                                                                                                           
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: POST / HTTP/1.1                                                                                                                                                                                                 
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Host: localstack.local.halter.io:4575                                                                                                                                                                           
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: User-Agent: aws-sdk-go/1.19.30 (go1.12.2; linux; amd64) APN/1.0 HashiCorp/1.0 Terraform/0.12.0-rc1                                                                                                              
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Content-Length: 137                                                                                                                                                                                             
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Authorization: AWS4-HMAC-SHA256 Credential=fakeAccessKey/20190519/ap-southeast-2/sns/aws4_request, SignedHeaders=content-length;content-type;host;x-amz-date, Signature=6d096165364670ac519063d10e916b38f0428adc
ee4296b645bc24df1079e54b                                                                                                                                                                                                                                                                   
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Content-Type: application/x-www-form-urlencoded; charset=utf-8                                                                                                                                                  
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: X-Amz-Date: 20190519T224448Z                                                                                                                                                                                    
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Accept-Encoding: gzip                                                                                                                                                                                           
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4:                                                                                                                                                                                                                 
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Action=ListTagsForResource&ResourceArn=arn%3Aaws%3Asns%3Aap-southeast-2%3A123456789012%3Ahalter-core_push_notification&Version=2010-03-31                                                                       
2019-05-19T22:44:48.251Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: -----------------------------------------------------                                                                                                                                                           
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: 2019/05/19 22:44:48 [DEBUG] [aws-sdk-go] DEBUG: Response sns/ListTagsForResource Details:
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: ---[ RESPONSE ]--------------------------------------                                                                                                                                                           
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: HTTP/1.1 500 Internal Server Error      
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Content-Length: 290                                           
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Access-Control-Allow-Headers: authorization,content-type,content-md5,cache-control,x-amz-content-sha256,x-amz-date,x-amz-security-token,x-amz-user-agent         
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Access-Control-Allow-Methods: HEAD,GET,PUT,POST,DELETE,OPTIONS,PATCH                                                                                                               
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Access-Control-Allow-Origin: *                                                                                                                                                                                  
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Content-Type: text/html                                          
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Date: Sun, 19 May 2019 22:44:48 GMT                                                                                                                                                                             
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: Server: BaseHTTP/0.6 Python/3.6.8                                                                                                                                                                               
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4:                                                      
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4:                
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: -----------------------------------------------------
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: 2019/05/19 22:44:48 [DEBUG] [aws-sdk-go] <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">  
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: <title>500 Internal Server Error</title>                                                                                                                                                                        
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: <h1>Internal Server Error</h1>                                                                                                                                                                                  
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: <p>The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.</p>
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: 2019/05/19 22:44:48 [DEBUG] [aws-sdk-go] DEBUG: Validate Response sns/ListTagsForResource failed, not retrying, error SerializationError: failed to decode query XML error response                             
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4:      status code: 500, request id:                                                                                                                                                                              
2019-05-19T22:44:48.268Z [DEBUG] plugin.terraform-provider-aws_v2.11.0_x4: caused by: expected element type <ErrorResponse> but have <title>
```

Is there any plan to support this tags API for SNS in localstack? If so is there anything that I could do to help out?
sub = get_subscription_by_arn(req_data['SubscriptionArn'][0])
                if not sub:
                    return make_error(message='Unable to find subscription for given ARN', code=400)
                content = '<Attributes>'
                for key, value in sub.items():
                    content += '<entry><key>%s</key><value>%s</value></entry>\n' % (key, value)
                content += '</Attributes>'
                return make_response(req_action, content=content)
            elif req_action == 'Subscribe':
                if 'Endpoint' not in req_data:
                    return make_error(message='Endpoint not specified in subscription', code=400)
            elif req_action == 'Unsubscribe':
                if 'SubscriptionArn' not in req_data:
                    return make_error(message='SubscriptionArn not specified in unsubscribe request', code=400)
                do_unsubscribe(req_data.get('SubscriptionArn')[0])
            elif req_action == 'DeleteTopic':
                do_delete_topic(topic_arn)
            elif req_action == 'Publish':
                
                
                if 'PhoneNumber' not in req_data:
                    if topic_arn not in SNS_SUBSCRIPTIONS.keys():
                        return make_error(code=404, code_string='NotFound', message='Topic does not exist')
                    publish_message(topic_arn, req_data)
                
                return make_response(req_action)
            data = self._reset_account_id(data)
            return Request(data=data, headers=headers, method=method)
        return True
    def _reset_account_id(self, data):