model: A basic implementation of ndn::ApiFace that can be used as an NDN handler in any "normal" NS-3 application

Refs #1005 (http://redmine.named-data.net/)
diff --git a/helper/ndn-app-helper.cc b/helper/ndn-app-helper.cc
index 58f62d3..d835da4 100644
--- a/helper/ndn-app-helper.cc
+++ b/helper/ndn-app-helper.cc
@@ -94,7 +94,7 @@
     }
 #endif
   
-  Ptr<App> app = m_factory.Create<App> ();        
+  Ptr<Application> app = m_factory.Create<Application> ();        
   node->AddApplication (app);
         
   return app;