Rewrite everything

This is moving toward a 0.2 release. I rewrote everything in another repository and finally got around to merging it into this one. 

The main change to the API is the introduction of the `/keys` endpoint. Now you can create an API key. Your entries will be stored under that key. 

On the back end, pretty much everything changed. Entries are stored in an IxSet. There's a better separation of "framework" and application code. I caved to Template Haskell.