R1:636eaf231ec4

Only show loading animation on thread change in Conpherence

Summary: Fixes the send on enter flash, only uses the `Threads` loading animation on changing threads, not sending a message.

Test Plan: Change threads, post a message.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D16705