Allow updating of objects

[ojongerius]

We currently check if an object exists, and if so, assume it is up to date.

Let's add functionality to update objects. This could be by supported in range of ways 2, not mutually exclusive options are to:

• Add support for PUT to replace an object with another version.
• Add support for PATCH to update the object in place.

Supporting PATCH is a little more subtle, and updating using it requires diffing the remote and local object, before PATCHING the remote object with the differences. PUT is brute force but will involve more network traffic.

[ojongerius]

both PUT and PATCH have been implemented and are documented at https://www.vol.community/api/swagger (needs auth to be visible)