Pass the json error in new callback parameter for jquery javascript client

When making request with jquery nuxeo client, the error passing to the callback is only showing related message to the http code error.

For instance, when making a failing GET:

nuxeo.js -> L549: callback(errorThrown, null, jqXHR)
-> errorThrown is only the code http message (e.g.: 404 -> Not found)

We could pass the jqXHR.responseText to pass the entire json error to the callback:

responseText: "{"entity-type":"exception","code":null,"status":404,"message":"user does not exis...