Cannot .init with a target jquery element

In [the docs](http://rivetsjs.com/docs/guide/#components)  it says I can do

``` javascript
rivets.init('my-app', $('body'), {user: user})
```

but in reality I need to do

``` javascript
rivets.init('my-app', $('body')[0], {user: user})
```

`rivets.bind` still seems to work with jquery elements

http://jsfiddle.net/axz3d57L/2/ test case
