Custom 404 with redirect

I think I have a solution for your 404 problem... This *should* take the URL they were trying to reach and append it to an anchor link & redirect to the correct URL. Defaults to the meta refresh in case the script fails.

`http://mainecivichackday.com/about/` => `http://www.civichack.me/2014/#about`

Couldn't fully test it because you need a custom URL to use custom 404 pages on github. But it should work (in theory)

Fixes #27