Add i18n, split files, add 404

* Move main entry point from `index.js` to `server.js`
* Add dependencies for `cookie-parser` and `i18n`
* Rearrange `server.js` variable initialization order
* Make jade pretty-print everywhere
* Add localisation
* Add prettily formatted error handling
* Add 404 page
* Move routes from `server.js` to their own subdirectory
* Move center align from body to form in CSS
* Scope selectors
* Add skeleton jade file
* Modify footer to be multiple p tags
* Add URL decoding where appropriate