Return reference UUID in header of response

[okafke]

Current Implementation

When uploading a revocation batch on the EU-gateway, the UUID of that batch is returned as an ETag in the header of the response. (This functionality is btw missing here, too). When uploading a reference to /trust/reference an UUID is also randomly assigned to that reference, but to retrieve that UUID we'd need to download all references and find the one we've uploaded.

Suggested Enhancement

I propose that the response to a successful reference upload contains the UUID assigned to that reference.

Expected Benefits

This would make it much easier to find, modify and delete a reference after it has been uploaded.