add missing copyright header (#992)

willemvd · lunny · commit 5f234ce2a5a5 · 2017-02-21T08:46:14.000+08:00
diff --git a/models/migrations/v16.go b/models/migrations/v16.go
@@ -1,3 +1,7 @@
+// Copyright 2017 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
 package migrations
 
 import (
