model: Another set of refactoring/renaming to make code compile (not tested yet)

Refs #1005 (http://redmine.named-data.net/)
diff --git a/examples/custom-apps/dumb-requester.h b/examples/custom-apps/dumb-requester.h
index 06ed812..c2340e0 100644
--- a/examples/custom-apps/dumb-requester.h
+++ b/examples/custom-apps/dumb-requester.h
@@ -52,8 +52,7 @@
 
   // (overridden from ndn::App) Callback that will be called when Data arrives
   virtual void
-  OnContentObject (const Ptr<const ndn::ContentObject> &contentObject,
-                   Ptr<Packet> payload);
+  OnContentObject (Ptr<const ndn::ContentObject> contentObject);
   
 private:
   void