Update copyright dates

Signed-off-by: phineas <phin@phineas.io>

LICENSE

@@ -176,7 +176,7 @@
 
    END OF TERMS AND CONDITIONS
 
-   Copyright 2013-2016 Docker, Inc.
+   Copyright 2013-2017 Docker, Inc.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

pkg/symlink/LICENSE.APACHE

@@ -176,7 +176,7 @@
 
    END OF TERMS AND CONDITIONS
 
-   Copyright 2014-2016 Docker, Inc.
+   Copyright 2014-2017 Docker, Inc.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

pkg/symlink/LICENSE.BSD

@@ -1,4 +1,4 @@
-Copyright (c) 2014-2016 The Docker & Go Authors. All rights reserved.
+Copyright (c) 2014-2017 The Docker & Go Authors. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are