model: A couple of tricks and fixes in NDN.cxx, so it will play nice with python bindings

Refs #1011 (http://redmine.named-data.net/issues/1011)
diff --git a/ndn.cxx/ndn-api-face.h b/ndn.cxx/ndn-api-face.h
index 4b88f51..78f482a 100644
--- a/ndn.cxx/ndn-api-face.h
+++ b/ndn.cxx/ndn-api-face.h
@@ -117,16 +117,7 @@
   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
-
-}
-}
+} // ndn
+} // ns3
 
 #endif // NDN_API_HANDLER_H