Add the settings needle that provides the 'workspace' tag back
    
    Removing this broke the GNOME apps test entirely because there
    was no GNOME 'workspace' needle any more.
    
    I don't like this needle much, we should probably use
    check_desktop_clean or something instead. But for now let's just
    put it back.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>