Update selection cuts code in order to have a file with options

This file with options (input_selectionCuts.py) allows you to change the jet
category, the used background fit scale factors, etc.
Merge branch 'tmpbranch' into Branch_7TeVanalysis
Reorganization of  input_selectionCuts.py and selectionCuts_MErds.py

I update the selectionCuts_MErds.py file with the version of the file that uses
an input file with options (input_selectionCuts.py). These files are in
pyrootScripts now
Replace lumi_totEl2011 by lumi_totEle2011 (the correct name value in zbbCommons)
replace lumi_totEl2011 by lumi_totEle2011 (the correct value in zbbCommons)
Added different Xsec in el and mu channel for ZHsignals (which take into account
the prescale due to the fact that only a certain fraction of events of the ZH
samples were used to produce ME weights)
introduce environment CMSSW_BASE variable in zbbCommons to point to data folder

This is needed now after the restructurization in folders inside python