Switch from rspec to testunit.
Base controller methods and cache config.
Documents controller, route, layout and view.

Basic functionality to get an item to the content store and display it
on a page. Views are very basic at this point, and controller just
passes the content hash directly to the page.
Tests for fetching/displaying content item.
Merge pull request #3 from alphagov/content-store

Serve basic pages from content-store