Selector Utils : Updating electron and muon selections to official top PAG selections

Here is an update to the Selector Utils package to ensure that the electron and muon selections are up-to-date with respect to the TOP PAG recommendations here : 

https://twiki.cern.ch/twiki/bin/view/CMS/TWikiTopRefEventSel

Changes include : 

Muons : add delta-beta to the isolation definition.
Electrons : Add the effective area correction, latest conversion rejection, etc.