'Use the refresh token supplied in the token info to get a new token.
:param  token_info: Dictionary containing current token information
:type   token_info: ``dict``
:return:  A dictionary containing updated token information.
:rtype:   ``dict``'

def refresh_token(self, token_info):

    if ('refresh_token' not in token_info):
        return self.get_new_token()
    refresh_request = {'refresh_token': token_info['refresh_token'], 'client_id': self.user_id, 'client_secret': self.key, 'grant_type': 'refresh_token'}
    new_token = self._token_request(refresh_request)
    if ('refresh_token' not in new_token):
        new_token['refresh_token'] = token_info['refresh_token']
    return new_token
