Need some sort of way to tell people that a large representation has not been generated

[calpaterson]

Brief overview

AS A user downloading a large representation that isn't in the repcache

I WANT to get some kind of error code to tell me to backoff (complete with HTML that auto-refreshes to retry download)

SO THAT I don't just get a 5xx error

Additional details

This needs the addition (sadly) of Celery to run the generation in the background

[calpaterson]

This now works