rel="canonical" for "/" over "Front Page"

We can't simply 301 redirect from "Front Page" to "/" because
"Front Page" is used as the slug when e.g. in /_edit
sitemap support.

Using the django-static-sitemap package here, as real-time generation of
sitemaps is wayyyy to slow given the number of URLs we have (66k+).

This will generate a sitemap (for pages - split by every 50k or so and
indexed together) every hour via celery, then ping google with an
update.