Conpherence - add crop

Summary:
mainly, this adds the image cropper - yay!

 - also removes the file image from the handle stuff I added in V1. now we do all this crazy photo stuff.

Test Plan:
 - uploaded a photo by dragging to header and noted 120 x 80 showed up on reload
 - uploaded a photo by dragging to edit dialogue spot and noted 120 x 80 showed up on reload
 - cropped a photo - noted it cropped right
 - cropped a photo again and again and again - seems like it crops okay

Reviewers: epriestley, chad

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2418, T2399

Differential Revision: https://secure.phabricator.com/D4790