Create an OptionParser
        prog_name - Name of a command
        subcommand - Name of a subcommand

def create_parser(self, prog_name, subcommand):
        """
        Create an OptionParser
        prog_name - Name of a command
        subcommand - Name of a subcommand
        """
        parser = OptionParser(prog=prog_name,
                              usage=self.usage(subcommand),
                              option_list=self.option_list)
        return parser