[CMAN] Limit outstanding replies
    
    This commit imposes a limit on the number of outstanding replies
    that a connection can have. This is to prevent a DoS attack that
    causes cman to eat all available memory by sending lots of requests
    and not reading the replies.
    
    The deafult is 128, it can be set in cluster.conf as
    <cman max_queued="1000"/>
    
    Signed-off-by: Christine Caulfield <ccaulfie@redhat.com>