Make object update routes via PUT standards-complaint

[teisenbe]

Currently we do a not-quite RFC 7396 thing over PUT (rather than PATCH) to perform object updates, which is not standards compliant. For now, let's standardize on doing a full PUT (re-specifying the entire object state) for the updates.

[davepacheco]

Thanks for taking this on! This will bring us into alignment with RFD 4.

[teisenbe]

De-assigning for now since I'm not actively working on this