Hovercard - add project images

Summary:
adds project images. Also fiddles with HTML + CSS just a bit so we have a "picture" column and a "details" column if a picture exists.

This keeps the details all in a nice column even if there are many details that end up being taller than the picture UI.

Fixes T3991.

Test Plan: looked at a task (no pic), project (pic w/ no details), and user (pic w/ many details) hovercard and all looked good on Chrome and Safari

Reviewers: epriestley, chad

CC: chad, Korvin, epriestley, aran

Maniphest Tasks: T3991

Differential Revision: https://secure.phabricator.com/D8483
Minor improvements to Diviner layout

Summary:
  - Render functions as `func()` for consistency/clarity.
  - Sort articles first.
  - Sort case insensitively.
  - Label the "no group" symbols.

Test Plan: Regenerated and examined docs.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D8480