Improved localization utilities and consistency

* Incorporated moment.js for Date localization (Addresses #198)
* Incorporated accounting.js for Number and currency localization (Addresses #199)
* Made current language more consistent. (It updates the language used by utilities and uses the cookie/browser language as the default language)

All of this together addresses #234 and depends on https://github.com/my-koop/module.core/pull/12. (Actually haven't tested it without, it probably works but the French money will be formatted using the default settings, that is the English ones)