Update language settings

With an empty `language` property value these changes are automatically assigned to the picker the current application language. I think this is a good solution for multilingual systems. Also, if specify a full code (eg `ru-RU`), the picker will first check for an `ru-RU` language and if not found will check for a `ru` language.
Architecture of the widget assumes that the locales directory is not empty​​. But if it happens, English will be used.