Tau gun based on the plugin Pythia8PtGun

Single Tau with Pt 20 to 100. Decay modes: tau- > nu_tau, pi-, pi0 ,   tau- > nu_tau, pi- 
Runs in CMSSW_6_2_0_SLHC6 with cmsDriver commands: 
--conditions auto:upgradePLS3 -n 10 --eventcontent FEVTDEBUG -s GEN,SIM --datatier GEN-SIM --beamspot HLLHC --customise SLHCUpgradeSimulations/Configuration/combinedCustoms.cust_phase2_BE5D --geometry ExtendedPhase2TkBE5D --magField 38T_PostLS1