Handle paths for translated content

Rails by default assumes anything after a full stop in a request path represents the format of the request. We override the constraints in the routing to ensure the entire request path makes it through to the controller so that we can handle paths for translated content.
It's probably worth disabling the formatted routes here as well for clairty.  See https://github.com/alphagov/content-store/blob/master/config/routes.rb#L3 for example.