Fix Content-Length for prettified responses

go/fake-http/fake-http.go

			if err != nil {
				log.Printf("Error: Prettyfying JSON: %s", err)
			} else {
				resp.Header.Set("Content-Length", fmt.Sprintf("%d", len(pretty)))
				resp.Body = ioutil.NopCloser(bytes.NewReader(pretty))
			}
		}