Add possibility to specify SSL protocol

[jniebuhr]

Fixes #107

[nelsou]

if (useSslConnection(params)) { factory.useSslProtocol(getSslProtocol(params)) }

shouldn't it be in the addConnection instead of the getChannel ?

[jniebuhr]

It seems to be a global setting which is not used on the connection but on the factory. So I assumed this was the right spot.

[compae]

Could you add some tests?? I think that you need to initialize the keyManager and the trustManager...

[jniebuhr]

Yes, I'll do that

[jniebuhr]

If the test should be some kind of integration test, you'll need to change the jenkins setup to include some RabbitMQ with SSL

[jniebuhr]

I've added the tests now. The image I used was https://github.com/roboconf/rabbitmq-with-ssl-in-docker
I had to change fail_if_no_peer_cert to false though, which makes sense.

[jniebuhr]

A TrustManager instance is added automatically by the driver. I didn't find anything about a KeyManager in the docs, but I assume you'll need that one for client cert auth.