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-name-components.cc b/model/ccnx-name-components.cc
index b551733..a7066de 100644
--- a/model/ccnx-name-components.cc
+++ b/model/ccnx-name-components.cc
@@ -58,7 +58,7 @@
 std::list<boost::reference_wrapper<const std::string> >
 CcnxNameComponents::GetSubComponents (size_t num) const
 {
-  NS_ASSERT_MSG (1<=num && num<=m_prefix.size (), "Invalid number of subcomponents requested");
+  NS_ASSERT_MSG (0<=num && num<=m_prefix.size (), "Invalid number of subcomponents requested");
   
   std::list<boost::reference_wrapper<const std::string> > subComponents;
   std::list<std::string>::const_iterator component = m_prefix.begin();