Adding first weights up/down variations and code to remove double-counted events for data

I defined all the variables and histograms related to the weights up/down variations for electrons, muons, jets, pileup and prefiring. I also added the different codes taken from David to remove the doule-counted events for data: removeEmptyFiles.py (also useful for MC) to remove empty root files, removeDoubleCounting.py to remove double-counted events and launchBatchJob_dataCounting.py to refill the histograms (the tree will be empty unfortunately). launchRemovalDoubleCounting.py automatizes all this process and launchRemovalDoubleCounting_2.sh moves the output root files in the correct directory. Warning: before using launchRemovalDoubleCounting.py, the launchBatchJob_data.py should be ran only with the first cut in TprimeAnalyser.cpp.