API

The start of a public api, which can then be used by mobile apps (like a RubyMotion app).

It's extremely basic - just rendering out the list of articles as JSON. 

Trimmed some attributes such as 'created_at' and 'updated_at' (which can be misleading if an editor re-used an article already in a certain position) via defining ``as_json`` on the model.

Something to note that may be an annoying in development: the routes file does have a subdomain constraint for 'api', expecting a route of:

``api.briefly.co.nz/v1/articles.json``

In development it might be helpful to add this to ``/etc/hosts``:

``127.0.0.1 api.briefly.local``

The API controller also only responds to json.