Merge pull request #50 from cowboy129/master

Simplify ConnectionActive Status, add serializer
Use SocketIOExtension(system).resolver instead of NamespaceExtension(system).resolver for transport
Moved stuffs of ConnectionActive sharding to itself;
renamed package.scala to socketio.scala;
bump the version to 0.1.2-SNAPSHOT
Defining ClusterReceptionistExtension in akka.extensions configuration
property to load the extensions when the actor system is started.
Interaged cluster code for ConnectionActive together, so these can be
used by everything, not only in Namespace class.
Renamed configuration property "spray.socketio.seed-nodes" to
"spray.socketio.cluster.client-initial-contacts"
Expose connection status