Summary:
Depends on D20353. Ref T13275. This is just some small quality-of-life fixes:

  - When you add items to menus, they currently go below the "Edit Menu/Manage Menu" links by default. This isn't a very good place for them. Instead, lock "edit" items to the bottom of the menu.
  - Lock profile pictures to the top of the menu. This just simplifies things a little.
  - Show more iconography hints on the "edit menu items" UI.
  - Add a "drag stuff to do things" hint if some stuff can be dragged.

Test Plan:
  - Added new items to a Portal, they didn't go to the very bottom. Instead, they went above the "Edit/Manage" links; a sensible place for them.
  - Viewed the "edit menu items" screen, saw more hints and visual richness.
  - Viewed/edited Home, Projects, Portals, Favorites

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13275

Differential Revision: https://secure.phabricator.com/D20355