add server timeout functionality plus docker test

[goldenccargill]

As mentioned in the keep alive section of the pulsar binary configuration here if the server stops responding to our pings when we have to assume the connection is no longer valid. We can't just rely on the transport to tell us if the connection is alive or not. I've implemented it based on any response from the server rather than specifically a pong, its open to debate if this is correct, I could go either way.

I've also added a test to demonstrate the bug which is fixed by my code in the PingPongHandler