Document using SSL / TLS for message bus (RabbitMQ) connection

[Kami]

Right now we don't have any docs how to use SSL / TLS for RabbitMQ authentication and connection (we have docs for that for MongoDB, but not for RabbitMQ).

We should add docs for it and also verify it works with the current code base (might need small changes in the docs to support it fully).

[Kami]

I confirmed using SSL connection works our of box. I will document that.

Supporting client side certificate auth will require some small code changes.

[Kami]

Resolves via #848, #850.