Trigger SF implementation

[rathjd]

Every trigger on simulation is not exactly as efficient on data. The difference is absorbed by a scale factor (with an uncertainty).
We need an infrastructure to absorb the trigger scale factor for muons (POG-provided, link on twiki and AN) and for electrons (Ruiz et al. are going to determine that, or we find an AN to cite this, I have a link to the TOP trigger summaries who reference also scale factors https://twiki.cern.ch/twiki/bin/viewauth/CMS/TopTrigger

Implementation in Utilities/ScaleFactor.cc