Pholio - finish off history view

Summary:
...bsasically add a "view mode" and play with that throughout the stack. Differences are...

 - normal mode has comments; history mode does not
 - normal mode has inline comments; history mode does not
 - page uris are correct with respect to either mode

 ...and that's about it. I played around (wasted too much time) trying to make this cuter. I think just jamming this mode in here is the easiest / cleanest thing at the end. Feel free to tell me otherwise!

This largely gets even better via T3612. However, this fixes T3572.

Test Plan: played around with a mock with some history. noted correct uris on images. noted no errors in js console.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T3572

Differential Revision: https://secure.phabricator.com/D6638