CMSSW_5_3_12_patch3

#1018: Unused variables error fixed for slc6 #1013: AT unit test fix – Check for unavailable files, not for non local ones #973: Added integration test for MET uncertainties #969: Added mc pu reweighting #967: Fixed the path to the input file in SmearedJetProducer #934: Added Hijing_PPb_MinimumBias_cfi.py #896: Fixed FixMatrixInjector, required after changes in reqMgr 0.9.79 #894: Add mva electron id function for pat electrons (from CVS HEAD) #869: SUSY pat – add cff files #750: Update the MEt Phi correction factors with latest version taken from CVS HEAD. It was not tagged and therefore lost during the git transition. It includes correction factors for Run2012 ABCD (ReReco) and Summer 13 JEC.