[Catalog-sig] start on static generation, and caching - apache config.

["Martin v. Löwis"]

> Next up I'm going to put a few functions into store.py.  Ones to check
> if a release has changed since a given date.  Also one to see if any
> changes at all have happened since a given date.

Is this really necessary? I think it would be sufficient to have a table
of name,version pairs that list the releases that have changed. This
table is filled on modification, and cleared by the regeneration.

Regards,
Martin