added setcurrentfolder missing in MuonIsolationDQM.cc
fixing crash when sumw2 is called more than one time
Merge pull request #6758 from deguio/fixSumw2ForElectrons

fixing crash when sumw2 is called more than one time
Merge pull request #6742 from folguera/MuonDQM_73X_MuonIsoFix

added setcurrentfolder missing in MuonIsolationDQM.cc
Merge remote branch 'origin/CMSSW_7_3_X' into CMSSW_7_0_X
Merge remote branch 'origin/CMSSW_7_4_X' into CMSSW_7_0_X