Remove the application menu

Summary:
Toss this completely as per discussion elsewhere. Basically it doesn't feel as useful as we imagined it would, and breadcrumbs from T1960 will replace the primary useful part (navigating up).

There's some more cleanup to do but I'll hit that in the next few diffs.

Closes T1828 as wontfix.

Test Plan: Viewed app + local, app-without-local interfaces. Saw no app menus.

Reviewers: chad

Reviewed By: chad

CC: aran, vrana

Maniphest Tasks: T1828, T1960

Differential Revision: https://secure.phabricator.com/D4033