Always render comment panel in Diffusion commit view
Summary: I'm going to stop showing changes for commits which touch 30,000 files, but still want to show the comment panel.
Test Plan: Looked at commits, saw comments. Mashed "Z"; haunted mode worked.
Reviewers: nh, vrana
Reviewed By: nh
CC: aran
Differential Revision: https://secure.phabricator.com/D4729