adding worker aggregate listeners (2)

retake on https://github.com/juriansluiman/SlmQueue/pull/76
@basz ah, I see [this line](https://github.com/zendframework/zf2/blob/b1e33265a731aab365aad59a7263f557d0cfdd08/library/Zend/ServiceManager/AbstractPluginManager.php#L198) in the abstract plugin manager. Learned something new (I only thought it was directly passed onto the plugins, but that's only the case for invokables).