Add support I18n for error messages

What do you think?

default i18n scope activerecord

`$RAILS_APP/config/locales/en.yml`
```yml
en:
  activerecord:
    errors:
      messages:
        email: "is not a valid email"
        simple_email: "is not a valid email"
        url: "is not a valid URL"
        ....
```

Must be own i18n scope or not?
Write rspec for the feature or not?