code: function responseStatus(res) {
    if (res.status >= 200 && res.status < 300) {
      return res;
    } else {
      var error = new Error(res.statusText);
      error.response = res;
      throw customError('responseStatus', error);
    }
  }
docs: responseStatus
  take a response and check the response `status` property
  if between 200-300 return the response object
  else throw a custom error
  @param  {Object} res
  @return {Object}