mattdrayer/api-progress-generator-fix: Repaired existence check

@martynjames @fredsmith -- here's an updated progress generator to run in the staging environment.  We may not want to take the current tip of master due to some recent changes to organizations which require some baking time in integration/QA.  So what we should do here is merge to master and then simply put a copy of generate_progress_entries.py on the staging server, then run it.
Seems as though we are working around a defect in `get_or_create` here - good for the management command, but perhaps we need to log a ticket to address the problem in `get_or_create` for next sprint?