Localization

[wakahuula]

The currently has localizations for en-US and de-DE.

Localizations must be added as a json file under /assets/locale and retain the order of the en.json file.
Supported locales have to be added in main.dart and app_localizations_delegate.dart.

[guastallaigor]

pt-BR done at #10.

[wakahuula]

Thanks again! I'll add the remaining references in the mentioned dart files.

[deatheguard]

Going to make French one :3

[wakahuula]

Thanks! 😊

[Aircoookie]

Made a Japanese localization! Since I'm German though it might be best to have a native look over it before merging :)