Move Conpherence Threads to new phid stuff
Summary: Ref T2715.
Test Plan: loaded conpherence, loaded a different thread, made a conpherence. also phid.query
Reviewers: epriestley
Reviewed By: epriestley
CC: aran, Korvin
Maniphest Tasks: T2715
Differential Revision: https://secure.phabricator.com/D6577