Started a JSON API

The beginnings of a JSON API so that we can have an interactive map.

Does this look like a nice API or fundamentally offensive? How to put new routes in a different module, not quite satisfied with the approach here. Maybe they don't need to be somewhere else.

I'd like the landing page to look like this:

![mockup](https://cloud.githubusercontent.com/assets/1448859/5083318/33231d98-6ef4-11e4-9492-15064bea6231.png)

map centred somewhere sensible (browser geolocation?), just one box where you either type the name of a place you want to turn into a hash or a hash which then shows you where it is. After pressing return you see a pin at the location with a little popup telling you address and hashes.

Probably also good to add something so I can just click on a spot to learn its hash.