Summary:
adds ye olde people widget. Features include
- handle-based display, so we get status for free. (Note less pretty than M14 would have it!)
- can add a person
- can remove a person
- can see the people already in the conpherence
Test Plan: added and removed people and noted they joined / re-added as appropriate. Tried to add someone already in the conpherence and got a "transaction has no effect" message
Reviewers: epriestley, chad
Reviewed By: epriestley
CC: aran, Korvin
Maniphest Tasks: T2399
Differential Revision: https://secure.phabricator.com/D5466
