Adding RIT, PIT, FIB, and CS to ccnx-l3-protocol.  Some small
rearrangements in the code
diff --git a/helper/ccnx-header-helper.cc b/helper/ccnx-header-helper.cc
index 288162c..85c88f1 100644
--- a/helper/ccnx-header-helper.cc
+++ b/helper/ccnx-header-helper.cc
@@ -34,7 +34,7 @@
 namespace ns3
 {
 
-Ptr<Header>
+CcnxHeaderHelper::Type
 CcnxHeaderHelper::CreateCorrectCcnxHeader (Ptr<const Packet> packet)
 {
   uint8_t type[2];
@@ -43,11 +43,11 @@
   
   if (type[0] == INTEREST_BYTE0 && type[1] == INTEREST_BYTE1)
     {
-      return Create<CcnxInterestHeader> ();
+      return CcnxHeaderHelper::INTEREST;
     }
   else if (type[0] == CONTENT_OBJECT_BYTE0 && type[1] == CONTENT_OBJECT_BYTE1)
     {
-      return Create<CcnxContentObjectHeader> ();
+      return CcnxHeaderHelper::CONTENT_OBJECT;
     }
 
   throw CcnxUnknownHeaderException();