added ClusterDeployer and relevant specs per #486

Also changed a bunch of Akka.Cluster test configurations to use
akka.remote.helios instead of akka.remote.netty

fixing bugs related to cluster router deployments

fixed a critical bug with cluster router management messages; added an example

fixed divide by zero error with consistent hash routers

Made ConsistentHashableEnvelope a subclass of RouterEnvelope

Ensures that the correct message is sent to its intended destination
without changing the signature of the ConsistentHashableEnvelope class
itself.

fixed a cluster group router deployment bug

In this case, routers attempting to add routees from additional
deployments where none are available resulted in an invalid operation
error that could crash the router. Made this call safe instead.