Summary: Fixes T2214. For objects which support ApplicationTransaction, use ApplicationTransactions to apply subscription action changes. Principally, this makes clicking "Subscribe" / "Unsubscribe" appear correctly in the transaction log.
Test Plan: Clicked "Subscribe" and "Unsubscribe" a on Macros and Mocks.
Reviewers: chad
Reviewed By: chad
CC: aran
Maniphest Tasks: T2214
Differential Revision: https://secure.phabricator.com/D4986
