Previously there was not a better place than QueueManager
for the getBufferQueueForJob() method, but now we have a
factory for BufferQueues. Since getBufferQueueForJob() is
basically generating buffer queues using a different set of
criteria, it makes since for it to be in the BufferQueueFactory
Remove batch management methods from QueueManager and have
the JobQueue class access the BufferQueueFactory's batch
management methods directly. This way there is no confusion as
to what queues the QueueManager's batch management methods would
be managing.