Hide answer box if you asked the question in Ponder

Summary: Fixes T9241. Users have a tendancy to assume Ponder is a "forum", make replying to your own question take an additional click.

Test Plan:
View my own question, see notice, click open answer box, reply. Visit not my question, see box as normal.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: cspeckmim, Korvin

Maniphest Tasks: T9241

Differential Revision: https://secure.phabricator.com/D13957