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.
The line wrapping is inconsistent here. You might consider this instead:

```
self.mock_task_status.assert_called_once_with(
    state=self.mock_constants.CALL_WAITING_STATE, task_type=self.task.name,
    task_id=str(self.mock_uuid.uuid4.return_value), tags=self.some_kwargs['tags'])
```