Connect to UMB and parse brew.sign.rpm
    
    UMB related configuration are put into dedicated config files,
    fedmsg.d/freshmaker-rh.py.disable and conf/configrh.py.
    
    Name freshmaker-rh.py.disable because fedmsg-hub listens on fedmsg by
    default when start freshmaker. When need to connect to UMB,
    freshmaker.py should have same content as freshmaker-rh.py.disable.
    
    Configure fedmsg-hub to use STOMP to connect to UMB and receive
    messages. Broker URLs, certificate and private key files can be
    configured via several new FRESHMAKER_STOMP_* environment variables.
    
    * FRESHMAKER_STOMP_URI, URIs of brokers separated by comma.
    * FRESHMAKER_STOMP_SSL_CRT, path to certificate file.
    * FRESHMAKER_STOMP_SSL_KEY, path to private key file.
    * FRESHMAKER_MESSAGING_TOPIC_PREFIX, part of queue name from the
      beginning to word VirtualTopic, e.g.
      /queue/Consumer.client-me.queue.VirtualTopic
    
    Major changes:
    
    * Make event parsers configurable along with handlers in config
    * Reuse load_classes to load event parsers and handlers from config
    * Modify several config to add internal configuration for event parsers
      and handlers
    * BrewRPMSignEvent is renamed to BrewSignRPMEvent, which is natrual
      to follow the part of topic name, that is brew.sign.rpm
    * Add event parse for BrewSignRPMEvent
    
    Signed-off-by: Chenxiong Qi <cqi@redhat.com>
    
    So no need of environment variable FRESHMAKER_INSIDE_RH
    
    Signed-off-by: Chenxiong Qi <cqi@redhat.com>