updated storage of flavour information in pat::Jet and added ioread rule for backward compatibility
Merge pull request #3602 from cms-btv-pog/UpdatedJetFlavourStorage_from-CMSSW_6_2_X_SLHC_2014-04-29-1400

Updated storage of flavor information in pat::Jet: Backport from 7_1_X to 6_2_X_SLHC