Support for not_queues

Hello,

I added support for a not_queues option to force the worker to skip over specific queues. I required this functionality so the workers would continue working on jobs with a blank queue, or anything else. Specifically I had jobs that HAD to be run on a sub-set of machines.

I looked for specs (for queue for example) to emulate, but was unable to find any.

Pull coming to DJ master shortly.

--Brian