Added config option generate_unnamed_unlocalized_routes

Set this option to `true` to add the behavior of `force_locale`, but with a named default route which behaves as if `generate_unlocalized_routes` is set to `true`, so a `people_path` will redirect to `/en` or `/es` depending on the value of `I18n.locale`.
generate_unnamed_unlocalized_routes behaves like generate_unlocalized_routes and force_locale when generating localized paths
Readme update
Merge pull request #37 from Narnach/untranslated-fallback

Force locales, but with a fallback for the untranslated url