Update to standard language code

The standard: http://www.w3.org/International/articles/language-tags/#region

or view source code of this url: https://www.google.com/preferences?hl=en#languages

`pt_BR` is renamed as `pt-BR`
Google: https://www.google.com/?hl=pt-BR

`zh` is renamed as `zh-CN`
Google: https://www.google.com/?hl=zh-CN

`zh_TW` is renamed as `zh-TW`
Google: https://www.google.com/?hl=zh-TW