Fix url wrong base if used with Express app.use()

If using Express 4 `app.use()` to mount certain routes paths, the req.url will be rewritten to reflect the mounted path. This has the effect of creating a wrong base resulting in an invalid computed signature. I changed to use `req.originalUrl` since it preserves the original path.

Author: tinnou

lib/passport-http-oauth/strategies/utils.js

@@ -26,7 +26,7 @@ exports.originalURL = function(req, defaultHost) {
                ? 'https'
                : 'http'
     , host = defaultHost || headers.host
-    , path = req.url || '';
+    , path = req.originalUrl || '';
   return protocol + '://' + host + path;
 };