add cluster support
Merge pull request #2 from cowboy129/cluster

add cluster support
Added config option actor-selection-resolve-timeout
Fixed log.warning on exceptions.
Fixed parsing multiple packets payload.
Config for mass connections.
Moved cluster relative classes to cluster package.
Merge branch 'cluster' into mergecluster

Conflicts:
	src/main/scala/spray/contrib/socketio/cluster/ConnectionActive.scala
	src/main/scala/spray/contrib/socketio/cluster/Namespace.scala
Tried to combine cluster relative code.
make some class Serializable for cluster, add multi-jvm test

use 'sbt multi-jvm:test' to run test