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

Refs #1005 (http://redmine.named-data.net/)
diff --git a/apps/ndn-consumer.h b/apps/ndn-consumer.h
index 7dd4cdc..bb9e30a 100644
--- a/apps/ndn-consumer.h
+++ b/apps/ndn-consumer.h
@@ -61,11 +61,10 @@
   // OnInterest (const Ptr<const Interest> &interest);
 
   virtual void
-  OnNack (const Ptr<const Interest> &interest, Ptr<Packet> packet);
+  OnNack (Ptr<const Interest> interest);
 
   virtual void
-  OnContentObject (const Ptr<const ContentObject> &contentObject,
-                   Ptr<Packet> payload);
+  OnContentObject (Ptr<const ContentObject> contentObject);
 
   /**
    * @brief Timeout event