R1:61e7043664ee

Make Ponder use ApplicationTransaction rendering for answers

Summary: Ref T3373. This breaks some stuff, but future diffs will fix it.

Test Plan: Viewed some questions, saw answer text.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, chad

Maniphest Tasks: T3373

Differential Revision: https://secure.phabricator.com/D6604