Since this middleware will be run on every single route, even invalid ones, this means that `req.url` can contain arbitrarily weird user data. Hopefully `statsd.increment()` is prepared to take this, and e.g. it's not possible for the incoming URL path to contain weird characters that crash statsd... If we're uneasy about that, we might want to filter `req.url` through a regexp or something that e.g. ensures it's a reasonable ASCII string, or something.