Pdigitizer dynamic ineff fpix

This is an extension of pixel digitizer's dynamic inefficiency feature for endcap disks in current detector as part of Run2 preparation.
New configurable variables: theInstlumiScaleFactor, bunchScale (which depends on bunchpace value).
Currently all config variables are under discussion with the tracker experts, the final factors will be in a different PR with config file changes only.
We need this change in order to re-scale the meaning of 1 PU when going from 8 TeV to 13 TeV. The track multiplicity per PU increases by 18% with the higher collision energy. The title of the PR is misleading in the sense that there are two changes additional to introducing inefficiency in FPix: correcting for higher energy and introducing a new variable to specialize for the 25 ns bunch spacing.