Minor teaks to scanEIT.py for ease of use.

Updated joblib code to detect number of cores automatically.
     --> I use this code on a 2 core machine and an 8 core machine. Don't want to change things by hand.
Defined Delta in terms of the Natural Linewidth.
     --> This is how we measure Delta in the lab.
Moved all B-field conversions into a single variable.
     --> I suspect the B-field conversion isn't quite right. Moving everything to one variable will make it easier to fix later on.