Change SetCutWeight to not return codes

No one currently checks the return status of this function, so set it to
void instead of returning "0" on success.
Add ZTriggerEfficiencies
Remove incorrect comment
Allow negative Eta values in EfficiencyTables

The Trigger will have both plus and minus eta values so we adjust
EfficiencyTable to allow that.

The current |eta| (reco, eg_tight, etc.) tables have been duplicated so
that there are identical values for both plus and minus eta.
Merge branch 'trigger_scale_factors'

Conflicts:
	ZFinder/Event/src/ZFinderElectron.cc