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/hijacker.cc b/examples/custom-apps/hijacker.cc
index 4213f97..a4d7601 100644
--- a/examples/custom-apps/hijacker.cc
+++ b/examples/custom-apps/hijacker.cc
@@ -45,9 +45,9 @@
 }
 
 void
-Hijacker::OnInterest (const Ptr<const ndn::Interest> &interest, Ptr<Packet> packet)
+Hijacker::OnInterest (Ptr<const ndn::Interest> interest)
 {
-  ndn::App::OnInterest (interest, packet); // forward call to perform app-level tracing
+  ndn::App::OnInterest (interest); // forward call to perform app-level tracing
   // do nothing else (hijack interest)
 
   NS_LOG_DEBUG ("Do nothing for incoming interest for" << interest->GetName ());