Decoupling busi nodes and conn/tran nodes.

1. move busi nodes out of the socketio cluster
2. busi nodes will register themselves to the cluster, and the cluster use ClusterNamespaceMediator to route (by RoundRobin etc.) OnPacket msg to one of the busi nodes within the same group (same system name).
Merge branch 'cowboy129-master'

Conflicts:
	src/main/scala/spray/contrib/socketio/LocalConnectionActive.scala