Rename /stories/sunlight to /stories/modern-approach-to-open-data

This is the same PR as #23 (I didn't have permissions to re-open it), but with a redirect at /stories/sunlight. It uses a 0 (immediate) timer to do the redirect, which [search engines treat as a 301](http://sebastians-pamphlets.com/google-and-yahoo-treat-undelayed-meta-refresh-as-301-redirect/). It also contains a `canonical` link href to the new post, in case that helps.

I believe Github Pages blocks all plugins, otherwise I'd have used [jekyll-pageless-redirects](https://github.com/nquinlan/jekyll-pageless-redirects/) to implement it.