Migrate Tau HLT DQM to DQMEDAnalyzer

Migrate HLTTauDQMOfflineSource to DQMEDAnalyzer. I split the old histogram booking to two parts: the HLT menu parsing that is done in dqmBeginRun() (now that it gets called before bookHistograms()), and the booking of histograms that is done in bookHistograms().

FYI @mbluj