Uninstall Conduit calls when uninstalling applications

Summary: Fixes T2698. When applications are installed, their Conduit calls should drop out. This will also let us land Releeph without exposing Conduit calls.

Test Plan:
  - Viewed Conduit console; uninstalled some applications and verified their calls dropped out.
  - Tried to make an uninstalled call; got an appropriate error.

Reviewers: edward, btrahan

Reviewed By: edward

CC: aran

Maniphest Tasks: T2698

Differential Revision: https://secure.phabricator.com/D5302