Conpherence - make pontificate be all ajaxy

Summary: serving up for some feedback -- does anything fancy need to happen when new messages load (say highlight em and fade the highlight out) or just scrolling down okay? in JS I have a TODO about how come it doesn't work; that code works okay in my console if I print out various debugging values and enter them in manually.

Test Plan: pontificate with myself; note new message and message entry updates properly. pontificate as different user then as myself; note two messages load and message entry updates properly. pontificate as a user who isn't the last to reply; note new message and message entry updates properly

Reviewers: epriestley, chad

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2522

Differential Revision: https://secure.phabricator.com/D5214