Allow revisions to be filtered by created date

Summary:
Ref T13202. See PHI906. This is a reasonable capability which we support in some other applications already.

(The only real reason not to support this is that it creates some clutter in the UI, but I think we're generally in better shape now than we were in the past, and we could make this UI collapse/fold at some point.)

Test Plan: Ran queries with a minimum date, a maximum date, both, and neither. Saw appropriate results in all cases.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13202

Differential Revision: https://secure.phabricator.com/D19732