* rabbitmq_binding: Fix using empty routing key
If the routing key is an empty string we need to use the special props
value ~ in the URL. Otherwise the last part of the URL will be empty,
which will instead be equivalent to the "list all bindings" API call
which always returns 200 OK (as long as the exchange and queue exists).
* rabbitmq_binding: Move routing_key test outside format
Test the routing_key value and set the props value outside the format
call. We leave the original routing_key untouched since its original
value is later needed in create().
Jordan Borean
Jon Bergli Heier
Dag Wieers