Making CcnxContentObjectHeader and CcnxInterestHeader to be inherited
from SimpleRefCount

This way we don't need to modify Chunk inheritance
diff --git a/model/ccnx-content-object-header.h b/model/ccnx-content-object-header.h
index 324f766..26e8333 100644
--- a/model/ccnx-content-object-header.h
+++ b/model/ccnx-content-object-header.h
@@ -24,6 +24,7 @@
 
 #include "ns3/integer.h"
 #include "ns3/header.h"
+#include "ns3/simple-ref-count.h"
 #include "ns3/trailer.h"
 #include "ns3/nstime.h"
 
@@ -51,7 +52,7 @@
  * 
  */
   
-class CcnxContentObjectHeader : public Header
+class CcnxContentObjectHeader : public SimpleRefCount<CcnxContentObjectHeader,Header>
 {
 public:
   /**
diff --git a/model/ccnx-interest-header.h b/model/ccnx-interest-header.h
index dcfd983..3e46541 100644
--- a/model/ccnx-interest-header.h
+++ b/model/ccnx-interest-header.h
@@ -24,6 +24,7 @@
 
 #include "ns3/integer.h"
 #include "ns3/header.h"
+#include "ns3/simple-ref-count.h"
 #include "ns3/nstime.h"
 
 #include <string>
@@ -125,7 +126,7 @@
    - InterestLifetime: ?
    - Nonce: 32 bit random integer.  If value is 0, will not be serialized
  */
-class CcnxInterestHeader : public Header
+class CcnxInterestHeader : public SimpleRefCount<CcnxInterestHeader,Header>
 {
 public:
   /**