Mutual peer dicovery

The dSM peer discovery mechanism based on JXTA is not really fast.. Indeed, a remote node is found by a peer when the former answers a specific request sent on intialization and then every 10 seconds (approximatively). Thus, a discovery may last 10 second in the worst scenario.. To make this process significantly faster, a mutual discovery should be achieved: when a peer discovers another one, it immediately notifies it about its presence. For this purpose, a new dSM message type should certainly be created.