b=3405

robert's fixes:
 - add CONNECT_INITAL flag for the initial connect message from a client.  When
   server sees an old client reconnect with that flag, then it needs to set the
   handles as if it was a new client.

 - set the initial imp_conn_cnt from the server's conn_cnt. When client
   connects with INITIAL set, the server sends back the old conn_cnt+1.

 - timeout for inter-MDS requests is set to obd_timeout / 2