Refactor utils/utils, fixes #11923

Signed-off-by: Antonio Murdaca <me@runcom.ninja>

httputils/httputils.go

@@ -0,0 +1,26 @@
+package httputils
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/docker/docker/pkg/jsonmessage"
+)
+
+// Request a given URL and return an io.Reader
+func Download(url string) (resp *http.Response, err error) {
+	if resp, err = http.Get(url); err != nil {
+		return nil, err
+	}
+	if resp.StatusCode >= 400 {
+		return nil, fmt.Errorf("Got HTTP status code >= 400: %s", resp.Status)
+	}
+	return resp, nil
+}
+
+func NewHTTPRequestError(msg string, res *http.Response) error {
+	return &jsonmessage.JSONError{
+		Message: msg,
+		Code:    res.StatusCode,
+	}
+}