AMQP-286 Conditional Declaration (Queues etc)

* Add a collection of AmqpAdmin to queues, exchanges, bindings; only declare if the collection is empty or this RabbitAdmin is in the collection.
* Add Schema/Parser changes/tests.
* Add Reference Doc
Merge pull request #106 from garyrussell/AMQP-286

* garyrussell-AMQP-286:
  AMQP-286 Conditional Declaration (Queues etc)