Remove stub internationalisation?

[tlongers]

the ~es locale is active in the version of the Handbook that is pushed to RTD, but is not translated.I set this up to provide a working localisation infrastructure (via Sphinx's own internationalisation feature and Transifex), but this has not been used. If we're not using it for now, there's no loss in removing it to keep the repo uncluttered; easy to restore when we do now we know how to do it. Views?