Aws sdk upgrade

Move to `aws-sdk-promise` and added `incidentId` to all HTTP 500 errors, which are now sent in a consistent manner. This is useful when a user gets an  HTTP 500 error, he also gets an `incidentId` we can then go to loggly and search for the incidentId in logs..

It's just a UUID, simple, crude and very useful, as it means we don't have to rely on timestamps.