* 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