Make rabbitmq session scope

- clear exchanges and queues

- tests
You're sure?

TCPExecutor eaits for succesfull connection to server: https://github.com/mlen/summon_process/blob/master/summon_process/executors/tcp_coordinated_executor.py#L16

While this waits also on rabbitctl.

I'd personally leave both, or eventually only the wait_for_rabbit