function setUpdateStateInJSON(key, value) {
         var result = $.Deferred();

        updateJsonHandler.set(key, value)
            .done(function () {
                result.resolve();
            })
            .fail(function () {
                resetStateInFailure("AutoUpdate : Could not modify updatehelper.json");
                result.reject();
            });
        return result.promise();
    }
Sets the update state in updateHelper.json in Appdata
@param   {string} key   - key to be set
@param   {string} value - value to be set
@returns {$.Deferred} - a jquery promise, that is resolved with
                      success or failure of state update in json file