model+ndn.cxx+apps: New application template (CallbackBasedApp) that can be used to prototype NS-3 applications in python

The current code allows simulating in python using ApiFace (passed basic tests)

Refs #1005 (http://redmine.named-data.net/)
diff --git a/ndn.cxx/ndn-api-face.h b/ndn.cxx/ndn-api-face.h
index 160540e..4b88f51 100644
--- a/ndn.cxx/ndn-api-face.h
+++ b/ndn.cxx/ndn-api-face.h
@@ -28,6 +28,8 @@
 #include <ns3/callback.h>
 #include <ns3/ndn-face.h>
 #include <ns3/ndn-name.h>
+#include <ns3/ndn-interest.h>
+#include <ns3/ndn-content-object.h>
 
 namespace ns3 {
 namespace ndn {
@@ -58,7 +60,7 @@
   /**
    * @brief Shutdown the API face
    */
-  void
+  virtual void
   Shutdown ();
   
   /**
@@ -115,6 +117,15 @@
   ApiFacePriv *m_this;
 };
 
+
+/// @cond include_hidden
+#ifdef PYTHON_SCAN
+struct CallbackVoidNameInterest : public Callback<void, Ptr<const Name>, Ptr<const Interest> > { };
+struct CallbackVoidInterestContentObject : public Callback<void, Ptr<const Interest>, Ptr<const ContentObject> > { };
+struct CallbackVoidInterest : public Callback<void, Ptr<const Interest> > { };
+#endif
+/// @endcond
+
 }
 }