Added a first draft for the spanish translation of the CoC.

This only translates `_code-of-conduct.md` which is most of the CoC, but I guess `index.html.erb` should also be translated. I'm not familiar with rails though, so I'm probably not the best person right now to do i18n work on that. I can definitely provide a translated copy of that file, but that's probably not the best way of doing it, right? 

If I'm wrong, I'll be happy to add that copy to this PR, just let me know.

This refers to issue #22.

Thanks!