Centralit initial commit
update
update
Multi-threading update.
update histogram ranges
Merge pull request #5194 from BetterWang/Centrality_from-CMSSW_7_2_0_pre4

DQM/Physics -- Centrality from cmssw 7 2 0 pre4
Merge remote branch 'origin/CMSSW_7_2_X' into CMSSW_7_0_X