Global app init bits:

        * set up API versions
        * validate authentication info

def initialize_app(self, argv):
        """Global app init bits:

        * set up API versions
        * validate authentication info
        """

        super(NeutronShell, self).initialize_app(argv)

        self.api_version = {'network': self.api_version}

        # If the user is not asking for help, make sure they
        # have given us auth.
        cmd_name = None
        if argv:
            cmd_info = self.command_manager.find_command(argv)
            cmd_factory, cmd_name, sub_argv = cmd_info
        if self.interactive_mode or cmd_name != 'help':
            self.authenticate_user()