Update analysis job objects

This adds some functionality to job objects that is needed for the commands selection page. Exists now properly checks the data used for the job, and delete now works for jobs.
Not really, as the current statement actually creates the dictionary structure in postgres, so the samples are multiple lists tied to their processed data ids. I can't think of a way to do the actual comparison in SQL itself because of that. If we were dealing with a single aggregated list of samples that would work though.