Change gae to apache 2 license.

service/datastore/datastore.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
+// Copyright 2015 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
 
 package datastore
 
 import (
         "fmt"
         "io"
         "io/ioutil"
         "os"
         "path/filepath"
         "reflect"
@@ skipping 497 matching lines @@
                 currentDir = filepath.Dir(currentDir)
         }
 }
 
 func filterStop(err error) error {
         if err == Stop {
                 err = nil
         }
         return err
 }