Updating copyrights

New format: 'Copyright .year-present Open Networking Laboratory'

Change-Id: I1a9e58b355b775e75245ad875a2d7a4df3f03098
diff --git a/web/gui/src/main/webapp/_dev/checkmark-xmark-icon.html b/web/gui/src/main/webapp/_dev/checkmark-xmark-icon.html
index 4c726fe..fe49a76 100644
--- a/web/gui/src/main/webapp/_dev/checkmark-xmark-icon.html
+++ b/web/gui/src/main/webapp/_dev/checkmark-xmark-icon.html
@@ -1,6 +1,6 @@
 <!DOCTYPE html>
 <!--
-  ~ Copyright 2015 Open Networking Laboratory
+  ~ Copyright 2016-present Open Networking Laboratory
   ~
   ~ Licensed under the Apache License, Version 2.0 (the "License");
   ~ you may not use this file except in compliance with the License.