Added rename.
Added deletions.

Or at least the first pass at deletions. I might change this up a bit.
Using "asset" now.

Well, "object" was way overloaded with Python and the Object Storage.
The plural and singlular of "data" and "datum" was kind of odd to work
with. And "item" is a bit overloaded with Python too. So I went with
"asset".
Updated get-tag to work with deleted assets.
Added ability to revert assets to older versions.