R1:2665970762bf

Basic Answer Wiki for Ponder

Summary: Adds an additional field for questions, an answer wiki, should should usually be community editable.

Test Plan: New question, edit question, no wiki, lots of wiki.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D14003