more humanization for Module.use

见代码：
```javascript
seajs.use(['jquery', 'my cmd module'], function (r1, mod) {
   console.log(r1)  //undefined
   console.log(mod)  // get my module exports correctly
})
```

其实我想这样
```javascript
seajs.use(['jquery', 'my cmd module'], function (mod) {
   console.log(mod)  // get my module exports correctly
})
```