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`.
import re
import json
import logging
import requests
from flask import Response as FlaskResponse
from six.moves.urllib_parse import urljoin
from requests.models import Response
from localstack.constants import APPLICATION_JSON, PATH_USER_REQUEST
from localstack.config import TEST_KINESIS_URL, TEST_SQS_URL
from localstack.utils import common
from localstack.utils.aws import aws_stack
from localstack.utils.common import to_str
from localstack.utils.analytics import event_publisher
from localstack.services.kinesis import kinesis_listener
from localstack.services.awslambda import lambda_api
from localstack.services.apigateway import helpers
from localstack.services.generic_proxy import ProxyListener
from localstack.utils.aws.aws_responses import flask_to_requests_response, requests_response
from localstack.services.apigateway.helpers import (get_resource_for_path,
    handle_authorizers, extract_query_string_params,
    extract_path_params, make_error, get_cors_response)
LOGGER = logging.getLogger(__name__)
PATH_REGEX_AUTHORIZERS = r'^/restapis/([A-Za-z0-9_\-]+)/authorizers(\?.*)?'
PATH_REGEX_USER_REQUEST = r'^/restapis/([A-Za-z0-9_\-]+)/([A-Za-z0-9_\-]+)/%s/(.*)$' % PATH_USER_REQUEST
class ProxyListenerApiGateway(ProxyListener):