Fix to work with newest pythia8 version: 8.183: SoftQCD:minBias changed to SoftQCD:nonDiffractive
Merge pull request #3064 from smuzaffar/from-CMSSW_5_3_X_2014-03-28-0200

pythia8 8.183 fix: SoftQCD:minBias changed to SoftQCD:nonDiffractive