Add a .queue_name method to CallQueue...

- We can't use `.name`, because it conflicts with logger or celluloid or
something.
- I also have the `.work` method return the celluloid actor doing the work, so that the queue instance is returned [here](https://github.com/adhearsion/electric_slide/blob/8043011fe8c6c632c42f5eb23b4b94e4d2eaf371/lib/electric_slide.rb#L19) and makes it into the `@queues` hash.