Solution to allow curators to monitor sumstats release

[ljwh2]

As a curator, I need a way to confirm that sumstats have been released as expected. When a submission has passed validation successfully, I need to see whether the submission is embargoed or not, and if not embargoed, whether files exist on the ftp. I need to see this information for all submissions including pre-publication submissions. This could be a feature in Depocuration UI.