get_parser() should return a parser

This is also breaking other cliff commands (e.g. complete) that rely on
the method returning a parser as expected rather than None.

Change-Id: If145c18e1664c16d0eba49a9ac334b1e97abdb5a

tripleoclient/v1/tripleo_config.py

@@ -54,6 +54,8 @@ class GenerateAnsibleConfig(command.Command):
                                    "ansible.log files."),
                             default=constants.UNDERCLOUD_OUTPUT_DIR)
 
+        return parser
+
     def take_action(self, parsed_args):
         self.log.debug("take_action(%s)" % parsed_args)
         if utils.get_deployment_user() != parsed_args.deployment_user: