Enable response parsing and converting (from text to JSON, e.g.) by usin...

...g the code from jQuery 1.9.1

I needed the same behaviour of $.ajax done by the original jQuery XHR and by the IE8/9 version prepared by your hook - a JSON object if the response content type was application/json.  Solving in the hook saves using JSON.parse at every place $.ajax is used.  Consider including it in the official version too, please.

   --- Ferda