Add btag algos and susy pruned gen for miniAOD V2

This PR is made starting from 709 plus #5519 
It adds one btag algo as requested in 
https://twiki.cern.ch/twiki/bin/view/CMS/MiniAODCSA14FollowUp 
and add keep statement in pruned gen particles for SUSY particles

the btag part is already propagated in 72X and 73X by recent updates of #5446 and #5449 
For the gen particles part  I will update #5525  and #5526  to propagate in 72X and 73X
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