RabbitMqProducer: Don't declare queue when publishing message to server named (exclusive) queue

Use-Case: MQ-based RPC call with anonymously declared queue (client-code: channel.declare())

MessageProducer does not redeclare queue since it would result in error anyway. Instead it just publishes response message to default exchange ("") assuming queue and default binding already exist.
Merge pull request #944 from celper/rabbitmq_publish_to_servernamed_queue

RabbitMqProducer: Don't redeclare queue when publishing to server named (exclusive) queue