Get Run object in a service from the preBeginRun stage
We get our geometry information for our geometry service from the art::Run object. Right now, that means we connect to the postBeginRun signal. However, people would like to create histograms, etc using that information at the start of a job. Clearly beginJob is not able to know about anything stored in an art::Run object, but beginRun would be a logical place to do such tasks. The problem is that the services only know about art::Run objects through the postBeginRun signal...we would really like our service to know about it before doing the beginRun step for the modules.