1124570 - Adds two-queue implementation for reserved resources

https://bugzilla.redhat.com/show_bug.cgi?id=1124570

This BZ implements this [design and TODO list](https://fedorahosted.org/pulp/wiki/TwoQueueReservedResourceDesign). Refer to that doc for more info on what is contained in this PR.
This is an interesting change that I had not anticipated, but I think it makes sense. We want to delete the missing worker ASAP, and putting it behind the huge line would significantly delay deleting it. This way it should happen much more quickly.