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.
Aren't worker names unique? Doesn't that mean that this query could never return anything different than 0 or 1 documents? If all of that is true this test doesn't seem necessary.