Migrate Slowvote comments to ApplicationTransactions
Summary:
Move comments from the old table to ApplicationTransactions. Patch dances around which objects it uses since I intend to delete the comment table.
NOTE: This temporarily disables comment writes. I'll restore them shortly.
Test Plan: {F50166}
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Differential Revision: https://secure.phabricator.com/D6454