update BeamHaloNavigationSchoolESProducer_cfi.py in order to have only one instance of the NavigationSchool producer
Merge pull request #3655 from mtosi/from-CMSSW_7_1_0_pre7_fixNavigationSchoolCFI

Reco -- Fix NavigationSchoolESProducer template
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X