Return a Response instead of attempting to decode HTML response as JSON for errors

[markerickson-wf]

For example, a 403 response (unauthorized) returns an HTML page, but go-rest attempts to decode the body as JSON, and returns a cryptic error such as "invalid character '<' looking for beginning of value" instead of a Response object with the status code.

See https://github.com/Workiva/go-rest/blob/master/rest/client.go#L100 for how a 404 is correctly handled.

Are there any cases where we want to attempt to decode a JSON response if we have a status other than 200 (or 20x)?