Slim's System App Remover

Originally based from AICP's commit here:
https://github.com/AICP/packages_apps_Settings/commit/cf6f3b95c134385916d4514c5e376d0e5c44e714

And also Dirty Unicorn's priv-app adaptation

This also adds ROM Control and Performance Control to safelist so they aren't
removed.

Creditz to fronti90, SlimRoms, AICP, and Dirty Unicorns