Add support to send more message-bus notifications on commits
    
    This commit adds two configuration keys: ALWAYS_STOMP_ON_COMMITS and
    ALWAYS_MQTT_ON_COMMITS which will tell the default hook to send
    notifications on these messages bus if they are properly set up for all
    commits made to pagure.
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr></pingou@pingoured.fr>