Switch on BTag from candidates in reco and provide corresponding PAT tools

This PR runs one candidate based tagging (exploiting the new fwk) in RECO.
The corresponding code in jetTools.py (and related PAT stuff) is also added.

@ferencek @pvmulder
well, I'd not mess up with the file right now as we have in parallel the update for 70X new miniaod product that I made cherrypicking this commit to start with.
We could eventually cleanup at some point but I do not see how this can be relevant