[MERGE] Kick off for spanish translations of the docs

[Martin Pool]

Martin Pool has voted tweak.
Status is now: Semi-approved
Comment:
That is pretty cool, thankyou very much and also thanks to Lucio.

I don't think we should wait to get an explicit review from a Spanish 
speaker, so I'm ok to just merge it as is.

The only structural change I'd suggest is that we should link to this 
from the documentation index, and if you could be so kind also add a 
Spanish index.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C2422be180805041130p3f7297d2kd2d72bf12703445e%40mail.gmail.com%3E