src: Update copyright notices for files modified in 2015

Change-Id: I44133f166a90e26887c1db8972aae651cdb72f01
Refs: #2352
diff --git a/tools/ndnsec/import.hpp b/tools/ndnsec/import.hpp
index f8bfedf..3a42c1b 100644
--- a/tools/ndnsec/import.hpp
+++ b/tools/ndnsec/import.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2013-2014 Regents of the University of California.
+ * Copyright (c) 2013-2015 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *