Add data-type for results.
Split out cache-updating expansion.
Add a few extensions to scotty.

Notably, negotiate from https://github.com/heyLu/hspec-tutorial makes an
appearance again. Content-negotiated goodies coming soon!
Content-negotiation for everyone.

Now we only need better errors (probably :), docs, more features and
accept a 'format' parameter for those poor users with browsers.
Make cabal happy (types and less imports).