Record who created geometry

[donno]

When a user creates geometry (i.e via a post to /api/geometry), it
should firstly, require the user to be login and it should record who
was logged in.

This is important for keeping track of who made something and their
ownership.

It may need to be possible for a user (service account) to impersonate a
another user for the purpose of uploading data on their behalf.