Summary: Fixes T12627. Updates FundInitiative and FundBacker with modular transactions.
Test Plan: Create an Initiative, back it with fake monies, close initiative, reopen, edit various fields.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin
Maniphest Tasks: T12627
Differential Revision: https://secure.phabricator.com/D17782
