PHUIList, PHUIDocument updates

Summary:
This diff covers a bit of ground.

- PHUIDocumentExample has been added
- PHUIDocument has been extended with new features
- PhabricatorMenuView is now PHUIListView
- PhabricatorMenuItemView is now PHUIItemListView

Overall - I think I've gotten all the edges covered here. There is some derpi-ness that we can talk about, comments in the code. Responsive design is missing from the new features on PHUIDocument, will follow up later.

Test Plan: Tested mobile and desktop menus, old phriction layout, new document views, new lists, and object lists.

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D6130