Removed wrapping when emulateJSON is true, can't see a reason for it.

Hi,

When setting emulateJSON to true the model's values get wrapped in `{model: …}`. This is the commit that where was introduced, and it seems to have been kept ever since:

> 302c0d5 John Wright Thu Oct 28 20:21:59 2010 -0600
>  Added Backbone.emulateJSON to enable the current behavior of syncing
>   and made sending the body as application/json without a wrapping model
>   param, the default

I haven't been able to find any reasoning/justification for the difference. It's not *only* emulating JSON if it wraps the data in the new keys, in my opinion, so I removed it.

Regards,
Iain