Ecal DQM update

This update is a major restructuring of the ECAL DQM code. Each "task" was previously defined as independent EDAnalyzer and was repeated for EB and EE; now there is only one EDAnalyzer for the DQM source and one for the client, and the individual tasks are called by the analyzer as worker sub-modules. This eliminates the repetition of common procedures (setting up the monitor elements, retrieving the collection from Event, etc.) among the tasks, and makes the development and management of the code simpler.
There is little change in terms of the quantities being monitored, but the appearance of some plots change as empty, unfilled bins were removed. Also, calibration-related histograms were taken out of the standard offline DQM sequence as they also were permanently empty.
A technical documentation is being prepared in https://twiki.cern.ch/twiki/bin/viewauth/CMS/EcalDQMDevelopmentManual