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.

It is not straightforward for sure. We'll live with 10+ replication I guess untill someone finds time to fix it. The problem is that these things always accumulate. Later the argument is "it is an old code we don't modify it". Now you (or the original author) introduce it, then people start to eventually copy it with time (as there is no other way without restructuring).