Update Conpherence to use EditEngine
Summary: Moves Conpherence to use EditEngine. This removes the "First Message" field, but I think that's ok until we have direct messaging of some sort, then maybe have built-ins cover that case.
- Visit /new/ and /edit/ for creating new rooms.
- Edit a room in full conpherence
- Edit a room in durable column
- grep for METADATA calls
Reviewed By: epriestley
Maniphest Tasks: T11729
Differential Revision: https://secure.phabricator.com/D16677