No need for backward-compatibility with the frontend this early in dev, we'll update it promptly.  Later on we need to be more flexible, though.

The timestamp should really be created by the celery task and passed to create_work() etc, so it is the same both for created and for the log entry.  

The store is responsible for created, updated etc, so it should just set those values directly in the Work, ignoring anything that might be passed in from the frontend.