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-producer.h b/apps/ndn-producer.h
index bce01d3..1563d12 100644
--- a/apps/ndn-producer.h
+++ b/apps/ndn-producer.h
@@ -48,7 +48,7 @@
   Producer ();
 
   // inherited from NdnApp
-  void OnInterest (const Ptr<const Interest> &interest, Ptr<Packet> packet);
+  void OnInterest (Ptr<const Interest> interest);
 
 protected:
   // inherited from Application base class.