fix to ZdcNtuple adding bunch group information, plus a fix to ZdcAnalysis

ZdcNtuple now has the bunch group bit mask (thanks to @tamartin). I also discovered that the new "global ZDC sum" with side=0 was breaking several things in the xAOD and ntuples - now fixed (by skipping side=0).

I would appreciate some expert opinion on ZdcNtuple.h -- it is evolved from some analysis code and so does direct read calls to StoreGate (a la AnalysisBase). If I need to migrate everything to handles, I will have to do that immediately, but I am curious if the limited use case (just in the ZDC Tier0 calibration loop) does not require that after all.