Use brew_task_id in ResultsDB messages to guess product version
    
    Gets Brew task ID from the UMB message instead of using additional Brew
    XMLRPC call.
    
    This also solves an issues with containers which store task ID in
    'container_koji_task_id' field (under 'extra' dict) instead of
    'task_id'.
    
    Signed-off-by: Lukas Holecek <hluk@email.cz>