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/pib.cpp b/src/security/pib/pib.cpp
index 511c96a..73f53d0 100644
--- a/src/security/pib/pib.cpp
+++ b/src/security/pib/pib.cpp
@@ -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).
  *
@@ -24,6 +24,7 @@
 
 namespace ndn {
 namespace security {
+namespace pib {
 
 Pib::Pib(const std::string scheme, const std::string& location, shared_ptr<PibImpl> impl)
   : m_scheme(scheme)
@@ -115,6 +116,6 @@
   return m_defaultIdentity;
 }
 
-
+} // namespace pib
 } // namespace security
 } // namespace ndn