Updated LocaleChoosingListener

This PR ties in with my previous one, introducing the i18n_prefix option. When requesting `example.com/` the bundle would redirect to `example.com/en/` (or the most appropriate locale). However, it didn't do so when requesting `example.com/i18n_prefix/`. 

The listener will now check if the requested path is a "landing" path that matches `''` or any of the prefixes used. If so, it redirects to the correct url with the necessary locale.