security: Remove old security framework

This commit also finalizes removal of CryptoPP dependency.

Change-Id: Ia670cbeaf21b28d3b93fd36bb3781da3ac822662
Refs: #4246, #3946
diff --git a/src/security/v2/key-chain.hpp b/src/security/v2/key-chain.hpp
index e564326..59bf8fb 100644
--- a/src/security/v2/key-chain.hpp
+++ b/src/security/v2/key-chain.hpp
@@ -1,5 +1,5 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
+/*
  * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
@@ -502,6 +502,9 @@
 } ndnCxxAuto ## TpmType ## TpmRegistrationVariable
 
 } // namespace v2
+
+using v2::KeyChain;
+
 } // namespace security
 
 using security::v2::KeyChain;