Fall back to `updated` if `published` isn't present.
Optionally read config from config.edn.
Only define the posts ref once.

This makes them *not* mysteriously disappear in development after
changing server.clj and reloading, which is WONDERFUL.

Seriously, this is something to remember.
Add a few more blogs/feeds to fetch.
Ensure only xml alternates are selected.
Add source for paul grahams essays.