Client can handle on HTTP error different common error formats

[krnkl]

Client can be more aware of a common error format in the response body.
I.e. in the code below we expect only error with specific format:

	if response.StatusCode != http.StatusOK {
		problem := problemJSON{}
		err := json.NewDecoder(response.Body).Decode(&problem)
		if err != nil {
			return errors.Wrap(err, "unable to decode response body")
		}
		return errors.Errorf("%s: %s", msg, problem.Detail)
	}

where problem looks like:

{
    "title": "InternalServerError",
    "detail": "Something bad happend",
    "status": 500,
    "type:": "https://httpstatuses.com/500"
}

However, Nakadi returns different type of error when request is not authorised, which is:

{
    "error": "unauthorized",
    "error_description": "Full authentication is required to access this resource"
}

Thus, this error is swallowed and only status code is returned which cannot sometimes properly identify the cause.