Ecaldqm harvesting migration

Migration of ECAL DQM harvesting modules under DQM/EcalMonitorClient and DQMOffline/Ecal. Passed standard DQM tests.
Automatically ported from CMSSW_7_2_X #5327
It's because the DQMStore (and thus DQMStore::IBooker) expects float* as the array of bin edges (https://github.com/cms-sw/cmssw/blob/CMSSW_7_3_X/DQMServices/Core/interface/DQMStore.h#L318), while the xaxis.edges is a double*.