added ex_rename() extention method to the driver

added test suite for the ex_rename() extention method

changed ex_rename() to ex_rename_node() extention method

Added the MockHttptestcase from ex_rename_node() extension method

changed ex_rename() to ex_rename_node() extention method

corrected the MockHttptestcase for ex_rename_node() method

Added a fixture for ex_rename_node() method