Addition of code for nSubjettiness and QJets

Yesterday I submitted a pull request (https://github.com/cms-sw/cmssw/pull/2414) with the nSubjettiness and QJets code, along with code for gluon tagging and pileup ID.  The gluon tagging and pileup ID code needs some work, but (I hope) all the code in this pull request is okay.