[#5] Fix typo in delete auth function
[#5] Change default auth for showing and listing jobs

Forward auth checks to harvest_source_update instead of
harvest_source_show, as job reports should only be visible to users that
can manage sources.
[#5] Cleanup the job controller actions
[#5] Add new finished field for harvest job

When the run command flags a job as finished, it will query the most
recent harvest object for this job and use its import_finished value as
the job finishing time.