Prompt for the user and password.

def _get_auth_from_console(self, realm):
        """Prompt for the user and password."""
        self.user, self.password = self.AUTH_MEMOIZE_INPUT.get(realm, (self.user, None))
        if not self.auth_valid():
            if not self.user:
                login = getpass.getuser()
                self.user = self._raw_input('Username for "{}" [{}]: '.format(realm, login)) or login
            self.password = getpass.getpass('Password for "{}": '.format(realm))
            Credentials.AUTH_MEMOIZE_INPUT[realm] = self.user, self.password

        return 'console'