Ticket 54 - job done callback
Bug Description: We need a way to cleanup after a job is done. A way for the
calling application to have the job callback during clean up is needed.
Fix Description: Add the job_done callback. Add the ns_job_create to make
testing easier and clearer
https://fedorahosted.org/nunc-stans/ticket/54
Author: wibrown
Review by: rmeggins (Thank you)!