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 something you have to watch out for with Mock - the above line doesn't assert anything, but it's also not an error ☹

s/one_assert/one.assert/