* 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().
* Simplify permission changing code for rabbitmq_user module
* Add check for multiple permission dicts for same host to rabbitmq_user module
* Add docstring for _get_permission method of rabbitmq_user
* Fix method that compares vhost permissions in rabbitmq_user
* Add tests for rabbitmq_user module
* Add helper function for simulating collections.Counter functionality
* ignore empty lines in rabbitmqctl output
this fixes a bug with rabbitmq 3.7.5
rabbitmqctl can return empty lines, breaking the rabbitmq_parameter module
especially in a new vhost, the command rabbitmqctl list_parameters -q -p <vhost> will return an empty line
* Strip empty line in rabbitmqctl output