Dynamic derivation configuration

[rsmith54]

It would be nice if we figured out the derivation on the fly rather than having to set it in the run scripts. @kpachal has volunteered for this exciting activity.

[lawrenceleejr]

Maybe this should actually be done at the xAH level? Might be appreciated by a larger community.
-L

[mattleblanc]

@kpachal ... this is an example of what you need to change, depending on the derivation you're using:

https://github.com/rsmith54/FactoryTools/blob/master/util/run_b4j.py#L43

"SUSY2KernelSkim" -> whatever is used in the derivation you're looking at. A list of these should pop out of the code when it crashes because it doesn't have the right one ... but there was some time a little while ago when it did not.