Fix breakage of Pholio
Summary: Removal of PholioMockEditor::applyCustomInternalTransaction() in D17868 broke creation of new mocks in Pholio. Puts the empty method back until we finish migrating Pholio to modular transactions.
Test Plan: Created some mocks, observed lack of unhandled exception.
Reviewers: Blessed Reviewers, epriestley
Reviewed By: Blessed Reviewers, epriestley
Subscribers: epriestley
Differential Revision: https://secure.phabricator.com/D17889