UI improvements

Change-Id: I8b3540f8a49c6a151d5cc54d9a49005e0a3c98d8
diff --git a/osx/preference-delegate.mm b/osx/preference-delegate.mm
index b6a6686..dd0bfaf 100644
--- a/osx/preference-delegate.mm
+++ b/osx/preference-delegate.mm
@@ -121,5 +121,12 @@
   [[NSWorkspace sharedWorkspace] openURL: pageURL];
 }
 
+-(IBAction)openCertificationPage:(id)sender
+{
+  NSURL *pageURL = [NSURL URLWithString:@"http://ndncert.named-data.net"];
+
+  [[NSWorkspace sharedWorkspace] openURL: pageURL];
+}
+
 
 @end