Adjust English locale, add international variant.

The international locale is provided in the same spirit as [`en_DK`](http://ivoras.net/blog/tree/2010-12-20.the-wonderful-en_dk-locale.html), a "Euro English" locale available on many Linux distros. The publish date is displayed in an ISO 8601 format with hours and minutes.

Instead of `DK` (Denmark), we choose [`XZ`](http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2#XZ), a code that NATO uses to refer to international waters.