19. Separate route, menu and content to get translated urls

In #18 we did not get translated URLs, only the {_locale} prefix. We can use the ContentBundle, MenuBundle and RoutingBundle documents directly to build all of this separately.

The decision between using SimpleCmsBundle or the ContentBundle is a rather fundamental one, it would be some effort to migrate existing content. To keep this diff manageable, I only add a new service menu with one item, rather than refactor all content.