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.

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

I noticed that the option could remain ticked but not actually enabled
if the alert box is cancelled.
Merge remote-tracking branch 'origin/jb-mr1-mod' into jb-mr1-mod