Feature: Copy job with new workflow version

[dleehr]

A use case that came up in yesterday's meeting was to re-run previous jobs with a new version of the workflow. Rather than expecting users to repeat their input data object, we should add a method to copy an existing job to a new job, specifying an alternate workflow version.

Assuming the job order is compatible with the new version, there will be minimal changes to the data model to accommodate this. The Job -> JobFileStageGroup relationship is 1:1, so we'd need to make that 1:many or copy the stage group as well.