Heppy integration 7 3 x

Added Heppy software framework to 7_3_X. 
This line is causing the warnings in the IBs: https://cmssdt.cern.ch/SDT/cgi-bin/buildlogs/slc6_amd64_gcc491/CMSSW_7_3_X_2014-11-07-0200/PhysicsTools/Heppy