rpc call leads to unnecerry exchange declaration

[Attila Fazekas]

https://www.rabbitmq.com/amqp-0-9-1-reference.html#constant.not-found
"Default Exchange

The default exchange is a direct exchange with no name (empty string) pre-declared by the broker. It has one special property that makes it very useful for simple applications: every queue that is created is automatically bound to it with a routing key which is the same as the queue name. "

http://www.amqp.org/specification/0-9-1/amqp-org-download
"One of the standard message properties is Reply-To, which is designed specifically for carrying the name
of reply queues."

Normally for an rpc response do not need to declare a new exchange, the default exchange is for helping this very simple situation.

Based on my captured nova traffic currently the exchange_name == bind_key == queue_name,
so changing the code to just use the default exchange should be simple,

For example: 'reply_50bb0f9278e94d3eb7125c90d9ecb878'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/179388

[OpenStack Infra (hudson-openstack)]

Change abandoned by Victor Sergeyev (<email address hidden>) on branch: master
Review: https://review.openstack.org/179388
Reason: This doesn't maintain for a long time, so should be abandoned. Mehdi, please restore this path if you plan to continue your work on it.