* @cfg {String} successProperty Name of the property from which to retrieve the success attribute used by forms.
* @cfg {String} root name of the property which contains the Array of row objects.
* @cfg {String} id Name of the property within a row object that contains a record identifier value.
+ * @cfg {Array} fields Array of field definition objects
* @constructor
* Create a new JsonReader
* @param {Object} meta Metadata configuration options