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.

Those numbers are part of an algorithm, and this is something quite general for the values coded. From a physicist point of view, I personally find easier to see the numbers directly in the code at the right place than defined somewhere in the class (as a real IT dev would probably does per default) and have to come back and forth in the code to see what are the values.