security: Move KeyChain to security::v1 namespace and deprecated it

Change-Id: Ic4b6915ca15998a83b410f3f8fac027f797ee7ca
Refs: #3098
diff --git a/tools/ndnsec/key-gen.hpp b/tools/ndnsec/key-gen.hpp
index 1384ac8..5be5ce7 100644
--- a/tools/ndnsec/key-gen.hpp
+++ b/tools/ndnsec/key-gen.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2013-2016 Regents of the University of California.
+ * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -85,7 +85,7 @@
 
   bool isKsk = (vm.count("dsk") == 0);
 
-  KeyChain keyChain;
+  ndn::security::v1::KeyChain keyChain;
   Name keyName;
 
   try {