dmq: force to send replicated messages from configured server address - as reported on list by Victor Kustov
dmq: Don't delete the original notification_peer on timeout

(cherry picked from commit e73aa4032873b3fca88bb809d6d4ce4f28c0f237)
dmq: Add init_callback() to API

The init_callback is called after DMQ has synced with the notification_peer.
This callback can thus be used to send/broadcast messages as early as
possible.
dmq: Let the handler know about the sending node

Try to find a node based on the from uri of the incoming request and hand
it to the request handler.
dmq: Add find_dmq_node_uri function to API - based on patch submitted by Andrey Rybkin.