Fix 'pt' locale key and add translations for pt-BR and pt-PT

Hello,

FYI, the default locale is 'pt-BR', not just 'pt'. You can check the full list on [rails-i18n repository](https://github.com/svenfuchs/rails-i18n#available-locales).

This pull request:
*  changes 'pt' key to 'pt-BR', the default portuguese locale key
*  adds pt-PT key for portuguese from Portugal
*  adds locale files for both pt-BR and pt-PT

Regards