Completely uninstall beta applications

Summary: Fixes T2357. In D4529, I recommended we just hide tiles for beta applications on installs without beta apps enabled. However, this creates at least a couple of issues, notably the stuff in T2357. The main app I was concerned wih Config, which we ended up un-beta'ing anyway, so I think this will probably solve more problems than it creates.

Test Plan: Verified routes for beta applications dropped out when beta was disabled. Verified "Customize Applications" no longer shows these applications.

Reviewers: ljalonen, chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T2357

Differential Revision: https://secure.phabricator.com/D4546