support for binary data in API Gateway

[Adam Leventhal]

See: https://aws.amazon.com/about-aws/whats-new/2016/11/binary-data-now-supported-by-api-gateway/

This would look like a peer to resources under an apigateway API:

apigateway:
  my-api:
    resources:
      ...
    binary_support:
      image/png: True
      image/jpeg: True
      application/octet-stream: True