Fix application order, curing "Log Out" of wanderlust

Summary:
Fixes T3894. The "Log Out" icon has moved away from its rightmost position in the menubar.

In rP2e5ac12, I added a "Policy" application. This was the root cause.

The reordering logic (below) is slightly wrong. The `array_select_keys()` call is actually using the //strings// (like "Admnistration") to select the groups, not the correct constants (like "admin"). Use the constants instead and get the expected group ordering.

Test Plan: Loaded page, "Log Out" is in the rightmost position.

Reviewers: btrahan, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T3894

Differential Revision: https://secure.phabricator.com/D7177