Made resources_controller play nice with rails_locale_detection

Two things break if you try to use rails_locale_detection with rc_rails, and set routes as follows:

      scope "/:locale", locale: /(#{I18n.available_locales.join("|")})/ do
         resources ...
      end

1. named_routes don't take into account default_url_options (eg :locale => 'it')

2. the :locale segment is considered as required when in reality is passed by RailsLocaleDetection

this patch solves both issues, not sure how generic this is... up to you to decide if it can make it to the main branch.