Add a few new strip recHit validation histograms

New histograms for  pileup bunch number, event number for in-time bunch (by subDet), and number of simHits associated with a given recHit (by subDet and layer).  Discussed at Tracker DPG meeting of Aug. 15, 2014:  https://indico.cern.ch/event/322710/
This PR is for the strips.