Add visual cues to configuration panels
    
    Make it easier to recognize which plugins are enabled and which are
    disabled. Also make it easier to recognize when a plugin has just changed
    state, by flashing its row (help also realize it may have moved up/down)
    
    Based on concept work by Petr Vobornik
    
    Signed-off-by: Simo Sorce <simo@redhat.com>
    Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>