add MET receipe

The MET group is planning to close the MET recipe by integrating it into either the CMSSW releases or the PAT recipes [https://github.com/cms-met/cmssw/issues/1].

This PR contains the commits in the current MET recipe. With this PR in the CMSSW, we can close the MET recipe for 5_3_X.

The commit https://github.com/TaiSakuma/cmssw/commit/ac3814e10a7b1af43e271b687eeee3c394147242?diff=split edits a file under DataFormats/METReco but doesn't change the data format. It only adds friend operators and won't require to update the checksum.  I am not sure if that is ok.

these have a pretty long history
https://hypernews.cern.ch/HyperNews/CMS/get/pkgAnnounce/137777.html
We've integrated quite a bit of analysis level code in 53X since then; I guess that was a bad timing back in Feb 2013.