Fix some quirkiness with Answer comments in Ponder

Summary: There is still some general buginess with answer comments, trying to work them out. This replaces timeline rendering into one offs (less performant) but resolves many bugs. Or if there is a more performant way, let me know? Also when leaving an answer comment, you currently get redirected back to the page, but both the comment form is still populated and you dont see your answer without a reload. I feel like I'm missing some magical parameter to pass, so just redirecting back to the question itself.

Test Plan: Leave lots of answer comments.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D13946