RootTools AutoHandle: Allow a handle to be marked as possibly failing, in that case it will not throw if the product is not in the event. Used for LHEEventProduct in TTHAnalysis module for Susy scans
Merge pull request #28 from gpetruc/RootTools_AllowMissingProducts-CMG_PAT_V5_18_from-CMSSW_5_3_14

RootTools AutoHandle: Allow a handle to be marked as possibly failing.