addPlotForFracChargeRelValMonitoring

Add two plots to the Tk DQM for the monitoring of frac. charged signal in relVals.
This changes were discussed at the PdmV/DQM Joint meeting of the 28th of october: https://indico.cern.ch/event/294179/

Hey,
just out of curiosity: how well is this going to play w/ the rest of the configuration? IIUC, these method is invoked "@compile-time' to produce an ad-hoc configuration following the description you supplied. But who is going to load this configuration? What will be its names? Is it coherent to have some parameters declared "implicitely" in C++ and some others explicitly in python?