Adding client and server heartbeat monitoring for streams.

I needed to tell the difference between the Java and PHP clients on the RabbitMQ Connections tab of the management plugin. Before the client field was empty so I cross referenced why. Really it has nothing to do with heartbeats it just helped me debug and watch the heartbeats via the plugin. Let me know if you want it split out. If you do please delete the pull request and I will re-submit.