Refactor netty transport creation.

[dfish3r]

Create TransportConfig to encapsulate transport configuration. Change TransportFactory to accept TransportConfig. Add unique IDs for connection factories to correlate with thread pool IDs. Use a latch to wait until pipeline handlers have been removed on connection close. (Handlers are removed async and not guaranteed to be removed when event pools are shutdown.) Make classes in the netty package package protected. Conform thread pool naming. Reduce logging verbosity by changing redundant debug logs to trace.