Use ReadStream for server connection and event bus

Signed-off-by: Julien Viet <julien@julienviet.com>
Rename Registration -> MessageConsumer

Signed-off-by: Julien Viet <julien@julienviet.com>
Use handler for tests that don't need a stream

Signed-off-by: Julien Viet <julien@julienviet.com>
Commented out test for now pending resolution of potential Netty issue where acceptor is not paused