Btag cond format

This is the implementation of the new b-tag conditions format, as presented in the last talk of the AlCaDB meeting on 2014 Nov 10: https://indico.cern.ch/event/350636/
using cerr (or cout) is not allowed in cmssw, please use the logError from the EDM MessageLogger (see https://twiki.cern.ch/twiki/bin/view/CMSPublic/SWGuideMessageLogger)