Settings: Privacy Guard support

 * Add toggle to InstalledAppDetails to enable/disable privacy guard flag on
   a per-application basis.
 * Add toggle to enable privacy guard by default for applications.

Change-Id: If03aa5319c520b6c4a78887f0f46ef1443ddaa83
privacy guard: Fix crash when uninstalling an app

 * Don't try to update the privacy guard flag while refreshing after an
   uninstall since the PM will throw an exception at us.

Change-Id: Idadb99fefc2861e871f6206b08c844dda742fa68