all: InterestHeader and ContentObjectHeader refactoring to Interest and ContentObject

refs #29
diff --git a/apps/ndn-consumer-cbr.cc b/apps/ndn-consumer-cbr.cc
index 84fdd18..6ddedd8 100644
--- a/apps/ndn-consumer-cbr.cc
+++ b/apps/ndn-consumer-cbr.cc
@@ -137,14 +137,14 @@
 ///////////////////////////////////////////////////
 
 // void
-// Consumer::OnContentObject (const Ptr<const ContentObjectHeader> &contentObject,
+// Consumer::OnContentObject (const Ptr<const ContentObject> &contentObject,
 //                                const Ptr<const Packet> &payload)
 // {
 //   Consumer::OnContentObject (contentObject, payload); // tracing inside
 // }
 
 // void
-// Consumer::OnNack (const Ptr<const InterestHeader> &interest)
+// Consumer::OnNack (const Ptr<const Interest> &interest)
 // {
 //   Consumer::OnNack (interest); // tracing inside
 // }