Remove global select of container unit in jQuery implementation

Hi,

Currently, in the jQuery implementation, in the set_up_html method, you build a container_div with an id=@container_id, and then on line 46, you select the container via ID. This isn't necessary, since you already have a reference to the element.

Normally, this would be no big deal, however, since you're doing a global $(), you're loosing the reference the scoped element that's passed in. For me, this is causing problems when I'm using backbone.js. 

Let me know if this causes any problems I'm unaware of. 

Thanks,

Evan