Conpherence - add back in custom images

Summary: Fixes T7254. This reverts the previous functionality, but makes pertinent updates like scaling the images to 35 x 35. Codebase had moved on quite a bit so far from a straight revert but nothing too tricky relative to the code that was here before. This does not allow for changing the images from the conpherence durable column view -- that would require some JS trickery, but also doesn't fit into the current notion of the column being "light". Can always modify this later.

Test Plan:

• from full conpherence, uploaded a square pic and things looked nice
• from full conpherence, uploaded a rectangular pic and wasnt happy, so reinvoked edit dialog and used crop control to make it better
• noted could not update picture from conpherence durable column
• used different user and noted could see custom picture

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: CodeMouse92, Korvin, epriestley

Maniphest Tasks: T7254

Differential Revision: https://secure.phabricator.com/D12648