ref: adding copyright headers and licensing files

Change-Id: I135f73159c3e010f7faf14f1215bbd74eb32c2cb
diff --git a/services/identity/internal/caveats/mock_caveat_selector.go b/services/identity/internal/caveats/mock_caveat_selector.go
index 6c20637..00412bf 100644
--- a/services/identity/internal/caveats/mock_caveat_selector.go
+++ b/services/identity/internal/caveats/mock_caveat_selector.go
@@ -1,3 +1,7 @@
+// Copyright 2015 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 package caveats
 
 import (