I wonder if we should store the original state of this property before we set it so that we can revert it back to whatever it was.  This will prevent this plugin from impacting other uses of `$.cookie`.  Something like:

```js
// declare this at the top of the method:
var cookie_json = $.cookie.json;

// do this right when you need it to be json, for example:
$.cookie.json = true;
$.cookie( 'tests', bstat.variations, { expires: 30 } );

// reset it back to whatever it was
$.cookie.json = cookie_json;
```