Support SNS integrations #5
Description
When an SNS integration is called, it should emit a "notification" or "sns" event to allow hooking this up with @studio/notifications.
When invoking a Lambda function with an SNS message, it must have this form: https://gist.github.com/yyolk/cd22e8a3faf7fd75997b
Also have a look here: http://stackoverflow.com/questions/34213464/aws-api-gateway-communicating-to-sns