koa-modules/koa-i18n — pull request #2 by zation (2014-11-13 16:14:53+00:00)
Title: remove .toLowerCase so that we can use uppercase when config locales

With current code, we only can setup the locale with lowercase:
```
app.use(i18n(app, {
directory: './locales',
//Must keep in lower case because of koa-i18n/index.js:105
locales: ['zh-cn', 'en-us'],
header: true
}));
```

Because when we get local name in `koa-i18n/index.js:105`, we directly modify local to lower case...