model: Returning back support for CCNb wire format

Refs #1008 (http://redmine.named-data.net/)
diff --git a/model/ndn-content-object.h b/model/ndn-content-object.h
index 6fa60dd..c79ddf9 100644
--- a/model/ndn-content-object.h
+++ b/model/ndn-content-object.h
@@ -122,6 +122,21 @@
   uint32_t
   GetSignature () const;
 
+  /**
+   * @brief Set key locator
+   * @param keyLocator name of the key
+   */
+  void
+  SetKeyLocator (Ptr<Name> keyLocator);
+
+  /**
+   * @brief Get key locator
+   *
+   * Note that only <KeyName> option for the key locator is supported
+   */
+  Ptr<const Name>
+  GetKeyLocator () const;
+  
   //////////////////////////////////////////////////////////////////
   /**
    * @brief Get payload of data packet
@@ -170,6 +185,7 @@
   Time m_timestamp;
   uint32_t m_signature; // 0, means no signature, any other value application dependent (not a real signature)
   Ptr<Packet> m_payload;
+  Ptr<Name> m_keyLocator;
 
   mutable Ptr<const Packet> m_wire;
 };