add minDeltaR variable for Zinv
Created by: fojensen
add EDProducer to calculate minimum deltaR between MadGraph photon and partons. see: http://www-hep.colorado.edu/~fjensen/02092016_deltaR/ It is useful for making the GJets and GJets0p4 MC samples orthogonal In the case when running on DY or Zinv MC the Z boson will take the place of the photon