OmniSwitch: fixes for handling disabled apps

Disabling apps is not sending a removed intent so make
sure we remove disabled apps from favorites on next update.
Also listen to PACKAGE_CHANGED to update package list
in that case and only if service is really running.

Change-Id: I73838d21f3e21988afd195df3cde59f862bc3ac2
Merge pull request #3 from omnirom/android-4.4

OmniSwitch: fixes for handling disabled apps