Pixel Dynamic Inefficiency factors for RUN2

Preparing the RUN2 parameters of the pixel dynamic efficiency in 'SLHCUpgradeSimulations/Configuration/python/postLS1Customs.py'. Both 50ns and 25ns cases are treated. The default parameters (for 2012 run conditions) are set in the 'SimGeneral/MixingModule/python/pixelDigitizer_cfi.py'. In the pixelDigitizer_cfi.py the module 4 factors are updated.