changes to DQM harvesting

Change the Harvest job splitter to have two distinct modes, Periodic and EndOfRun that do not overlap.
In StdBase automatically add an additional EndOfRun DQM Harvest task if a Periodic DQM Harvest task is
specified. The EndOfRun task will trigger when the Periodic task is complete.
Merge pull request #4459 from hufnagel/harvestchanges

changes to DQM harvesting