all: InterestHeader and ContentObjectHeader refactoring to Interest and ContentObject

refs #29
diff --git a/examples/custom-apps/hijacker.h b/examples/custom-apps/hijacker.h
index 84d9070..07185de 100644
--- a/examples/custom-apps/hijacker.h
+++ b/examples/custom-apps/hijacker.h
@@ -39,7 +39,7 @@
 
   // Receive all Interests but do nothing in response
   void
-  OnInterest (const Ptr<const ndn::InterestHeader> &interest, Ptr<Packet> packet);
+  OnInterest (const Ptr<const ndn::Interest> &interest, Ptr<Packet> packet);
 
 protected:
   // inherited from Application base class.