fixed express child route jump correct

[sobird]

`var express = require('express');
var router = express.Router();
var CASAuthentication = require('cas-authentication');

var cas = new CASAuthentication({
cas_url : '',
service_url : ''
});

router.get('/', cas.bounce, function(req, res, next) {
// to
})`

例如上面代码按原来将会错误跳转，导致认证失败