add comments

cipher.go

@@ -1,3 +1,7 @@
+// Copyright 2015 The Xorm 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 xorm
 
 type Cipher interface {

databook.go

@@ -1,3 +1,7 @@
+// Copyright 2015 The Xorm 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 xorm
 
 import (

dataset.go

@@ -1,3 +1,7 @@
+// Copyright 2015 The Xorm 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 xorm
 
 import (

des.go

@@ -1,3 +1,7 @@
+// Copyright 2015 The Xorm 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 xorm
 
 import (