The following example `serverless.yml` fails to deploy on localstack:

```yaml
service: "localtest"

provider:
  name: "aws"
  runtime: "nodejs10.x"

functions:
  hello:
    handler: "handler.hello"
    
resources:
  Resources:
    ApiGatewayRestApi:
      Type: "AWS::ApiGateway::RestApi"
      Properties:
        Name: "${self:provider.stage}-${self:service}"
    GatewayResponseDefault400:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "DEFAULT_4XX"
        ResponseTemplates:
          application/json: '{"errors":[{"message":"Custom text."}]}'
    GatewayResponseUnauthorized:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "UNAUTHORIZED"
        ResponseTemplates:
          application/json: '{"errors":[{"message":"Custom text!", "extra":"Some extra info"}]}'
    GatewayResponseDefault500:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "DEFAULT_5XX"
        ResponseTemplates:
          application/json: '{"errors":[{"message":$context.error.messageString}]}'
    GatewayResponseIntegrationTimeout:
      Type: "AWS::ApiGateway::GatewayResponse"
      Properties:
        RestApiId:
          Ref: "ApiGatewayRestApi"
        ResponseType: "INTEGRATION_TIMEOUT"
        ResponseTemplates:
          application/json: '{"errors":[{"message":$context.error.messageString}]}'

plugins:
- "serverless-localstack"

custom:
  localstack:
    stages:
      - "local"
```

The error on the localstack end is `Exception: CloudFormation deployment for resource type ApiGateway::GatewayResponse not yet implemented`.
LOG.debug('Extract resource attribute: %s %s' % (resource_type, attribute))
    
    if resource_type == 'Lambda::Function':
        actual_attribute = 'FunctionArn' if attribute == 'Arn' else attribute
        return resource['Configuration'][actual_attribute]
    elif resource_type == 'DynamoDB::Table':
        actual_attribute = 'LatestStreamArn' if attribute == 'StreamArn' else attribute
        value = resource['Table'].get(actual_attribute)
        return value
    elif resource_type == 'ApiGateway::RestApi':
        if attribute == 'PhysicalResourceId':
            return resource['id']
        if attribute == 'RootResourceId':
            resources = aws_stack.connect_to_service('apigateway').get_resources(restApiId=resource['id'])['items']
            for res in resources:
                if res['path'] == '/' and not res.get('parentId'):
                    return res['id']
    elif resource_type == 'ApiGateway::Resource':
        if attribute == 'PhysicalResourceId':
            return resource['id']
    return resource.get(attribute)
def resolve_ref(stack_name, ref, resources, attribute):