add nutple for conversion region

values are ~consistent with what we get from the histograms
(see comparison in my slides from today's WH)
Some things need to be polished, but it's good enough to get
it going and try to make a new fake prediction.
compute_fake_el_scale_factor: also allow conversion sf

added a bunch of options to switch between teh bbcc scale factor
and the conversion one. Also rename some of the histograms/nutple
filenames.