Integration of MVA/NoPU MET in central release

This PR contains the MVA and NoPU code the JetMET group wants to make available centrally, and eventually computed at the RECO and miniAOD level after discussion with the RECO/AT group.

This PR add the package RecoMET/METPUSubtraction, and add the pat configuration files needed for the MET uncertainty tool.
Several fixes and cleaning are also done on the patCaloMET configuration, the pileupjetid configuration, the pileupJetid training needed by the MVA and NoPU MET.

As you said the routine is similar. Let me say it differently - if the convention for  vtxAssociationType changes from 0,...,3 to 1,...4 both places should be changed consistently. Or if one of the four should be dropped for some reason. The inputs may not be the same but the processing and the result (vtxAssociationType) are the same. It is pretty much the same function (and code) with different inputs.