When I Archive / Delete an App, its Gallery entry should be hidden

(User Story, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Apps
Summary: This should probably be automatic.
The definition of "Hidden" isn't entirely clear here, but it shouldn't be as available for use.
Once we have Unarchive, it should be be possible to re-list the App.