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 = logging.getLogger(__name__)
CURRENTLY_UPDATING_RESOURCES = {}
RUN_SERVER_IN_PROCESS = False
MODEL_MAP = {
    'AWS::StepFunctions::Activity': service_models.StepFunctionsActivity,
    'AWS::SNS::Subscription': service_models.SNSSubscription
}
def start_cloudformation(port=None, asynchronous=False, update_listener=None):
    port = port or config.PORT_CLOUDFORMATION
    backend_port = DEFAULT_PORT_CLOUDFORMATION_BACKEND
    print('Starting mock CloudFormation (%s port %s)...' % (get_service_protocol(), port))
    start_proxy_for_service('cloudformation', port, backend_port, update_listener)
    if RUN_SERVER_IN_PROCESS:
        cmd = 'python "%s" cloudformation -p %s -H 0.0.0.0' % (__file__, backend_port)
        env_vars = {'PYTHONPATH': ':'.join(sys.path)}
        return do_run(cmd, asynchronous, env_vars=env_vars)
    else:
        argv = ['cloudformation', '-p', str(backend_port), '-H', '0.0.0.0']
        thread = FuncThread(start_up, argv)
        thread.start()
        return thread
def set_moto_account_ids(resource_json):
    def fix_ids(obj, **kwargs):
        if isinstance(obj, dict):
            for key, value in obj.items():
                if 'arn' in key.lower() and isinstance(value, six.string_types):
                    obj[key] = value.replace(TEST_AWS_ACCOUNT_ID, MOTO_ACCOUNT_ID)
        return obj
    return recurse_object(resource_json, fix_ids)
def get_entity_id(entity, resource_json=None):