Move the NDNPing wrapper method to a helper class.

Also updates GPL header for the current calendar year.

Refs: #3492

Change-Id: Ic4977c33edd0311b140e6db3688afbb182acec9e
diff --git a/ndn/ndn_host.py b/ndn/ndn_host.py
index 7596f5f..2567794 100644
--- a/ndn/ndn_host.py
+++ b/ndn/ndn_host.py
@@ -1,6 +1,6 @@
 # -*- Mode:python; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
 #
-# Copyright (C) 2015-2017, The University of Memphis,
+# Copyright (C) 2015-2018, The University of Memphis,
 #                          Arizona Board of Regents,
 #                          Regents of the University of California.
 #