Make BE a bit more intelligent

When doing a tape to tape duplicate BE just grabs any available tape loads it up and then sits there waiting for other resources to become available blocking the use of drives for other jobs.

It would make more sense for BE to check if resources are available and if not queue the tapes in a queue the job so that other jobs that other duplicate jobs that start afterwards are not stopped from running by drives not being available even though they are not actually being used.