Reuse serialized data in Router

[jimfcarroll]

With dynamic topology the likelihood of forks in the processing pipeline increases, but the fact is an entire topology PROBABLY uses the same serializer. In this case it makes sense to reuse the serialized data in the transport.send method rather than reserialize the object to be sent.

[jimfcarroll]

The 0.9 codebase currently in master allows has made serialization an implementation detail of the transport. The NioTransport is "zero copy" but if the message is sent to multiple nodes it will be reserialized in each one. This wont be addressed any time soon.