Move config to v7 to fix previous v6 bug on null Notification entries. (#2650)

Thanks to @koolhead17 for reporting this.

cmd/utils_test.go

@@ -25,14 +25,14 @@ import (
 // Tests http.Header clone.
 func TestCloneHeader(t *testing.T) {
 	headers := []http.Header{
-		http.Header{
+		{
 			"Content-Type":   {"text/html; charset=UTF-8"},
 			"Content-Length": {"0"},
 		},
-		http.Header{
+		{
 			"Content-Length": {"0", "1", "2"},
 		},
-		http.Header{
+		{
 			"Expires":          {"-1"},
 			"Content-Length":   {"0"},
 			"Content-Encoding": {"gzip"},