Implementing notion of default routes (useful for Flooding scenarios)

Also, correcting SEGFAULT upon termination (when apps was destroyed
after ccnx stack)

Correcting LongestPrefixMatch to be able to perform default match
diff --git a/model/ccnx-fib.cc b/model/ccnx-fib.cc
index 0df2ded..89e5231 100644
--- a/model/ccnx-fib.cc
+++ b/model/ccnx-fib.cc
@@ -182,7 +182,7 @@
 {
   const CcnxNameComponents &name = interest.GetName ();
   for (size_t componentsCount = name.GetComponents ().size ();
-       componentsCount > 0;
+       componentsCount >= 0;
        componentsCount--)
     {
       CcnxNameComponents subPrefix (name.GetSubComponents (componentsCount));