Summary: Ref T6920, This removes the PonderVotableInterface from PonderQuestion and assocaited code. Also... never used?
Test Plan: Visit Ponder, See List, New Question, Add Answer.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin
Maniphest Tasks: T6920
Differential Revision: https://secure.phabricator.com/D13833
