security: Adapt PIB to NDN Certificate Format version 2.0

The certificate format can be found at docs/specs/certificate-format.rst

Change-Id: I5656837f09ce327e06a0cb1abdf16ac28fe0b823
Refs: #3202
diff --git a/src/security/pib/identity-container.hpp b/src/security/pib/identity-container.hpp
index 1de18c7..1ac30e1 100644
--- a/src/security/pib/identity-container.hpp
+++ b/src/security/pib/identity-container.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).
  *
@@ -27,6 +27,7 @@
 
 namespace ndn {
 namespace security {
+namespace pib {
 
 class PibImpl;
 
@@ -88,6 +89,10 @@
   shared_ptr<PibImpl> m_impl;
 };
 
+} // namespace pib
+
+using pib::IdentityContainer;
+
 } // namespace security
 } // namespace ndn