Route Maniphest comments/detail edits through new code

Summary: Ref T2217. When you add comments (or use that interface to make updates), ship it through the new code.

Test Plan: Added comments, made other changes to Maniphest tasks.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2217

Differential Revision: https://secure.phabricator.com/D7088