Parse token and secret from raw token response.

def parse_raw_token(self, raw_token):
        "Parse token and secret from raw token response."
        if raw_token is None:
            return (None, None)
        qs = parse_qs(raw_token)
        token = qs.get('oauth_token', [None])[0]
        secret = qs.get('oauth_token_secret', [None])[0]
        return (token, secret)