Queue module

Adding a Queue module to support testing with queue servers (Simple Queue Service).

Supported Queue Services
* Amazon's SQS
* Iron.io
* Beanstalkd
Here you are basically asserting that `$this->_getMessagesTotalCountOnQueue($queue) == $this->_getMessagesTotalCountOnQueue($queue)`. I guess, this would make more sense:
```php
$this->module->seeQueueHasTotalCount('default', 1);
```