Use application PHIDs in Paste

Summary: Ref T2715. Switch Paste to application PHIDs.

Test Plan: Used `conduit.query`; `conduit.lookup`; grepped for constants.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2715

Differential Revision: https://secure.phabricator.com/D6555