The locale name isn't translated in the promobox

[terw-dan]

As reported by @afercia in #15 (comment) the locale name isn't translated, but always in English, no matter the site language or user language.

[afercia]

A while ago I've played a bit with the GP plugin, turns out the locale native_name is available (check for example the gp/api/languages endpoint). It would just need to be added to the projects endpoint but that would require to hack the plugin (it's a two line change):