Introducing a couple of real test cases.

Also, basic PIT test shows that everything works as expected...

There was one big change in PIT. Previously, when PIT entry was
satisfied, it was immediately removed. As of recently, PIT entry is
immediately removed.
diff --git a/model/ccnx-fib-impl.h b/model/ccnx-fib-impl.h
index 2768a7d..eaedeee 100644
--- a/model/ccnx-fib-impl.h
+++ b/model/ccnx-fib-impl.h
@@ -25,7 +25,7 @@
 #include "ns3/ccnx-name-components.h"
 
 #include "../utils/trie-with-policy.h"
-#include "../utils/empty-policy.h"
+#include "../utils/counting-policy.h"
 
 namespace ns3 {
 
@@ -35,7 +35,7 @@
   typedef ndnSIM::trie_with_policy<
     CcnxNameComponents,
     ndnSIM::smart_pointer_payload_traits<CcnxFibEntryImpl>,
-    ndnSIM::empty_policy_traits
+    ndnSIM::counting_policy_traits
     > trie;
 
   CcnxFibEntryImpl (const Ptr<const CcnxNameComponents> &prefix)
@@ -62,7 +62,7 @@
   typedef ndnSIM::trie_with_policy<
     CcnxNameComponents,
     ndnSIM::smart_pointer_payload_traits<CcnxFibEntryImpl>,
-    ndnSIM::empty_policy_traits
+    ndnSIM::counting_policy_traits
     > type;
 };
 
@@ -109,6 +109,9 @@
   virtual void
   Print (std::ostream &os) const;
 
+  virtual uint32_t
+  GetSize () const;
+
   virtual Ptr<const CcnxFibEntry>
   Begin ();