Add bindings for I18nManager

I think there's no bindings for React Native I18nManager module. Github search of _I18nManager _ in this repository showed no result.

If someone could confirm that it is missing and that it should be added, I might do a pull request for its bindings.

Yeah that's missing for sure. PRs are always open!

I will have a look when I get back from vacations, around mi-september.