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/examples/ndn-simple-api.cc b/examples/ndn-simple-api.cc
index ba79af7..587ca55 100644
--- a/examples/ndn-simple-api.cc
+++ b/examples/ndn-simple-api.cc
@@ -75,15 +75,14 @@
 
   // Consumer
   ndn::AppHelper consumerHelper ("ns3::ndn::ApiApp");
-  // // Consumer will request /prefix/0, /prefix/1, ...
-  // consumerHelper.SetPrefix ("/prefix");
-  // consumerHelper.SetAttribute ("Frequency", StringValue ("10")); // 10 interests a second
+  consumerHelper.SetPrefix ("/prefix");
   consumerHelper.Install (nodes.Get (0)); // first node
 
   // Producer
   ndn::AppHelper producerHelper ("ns3::ndn::Producer");
   // Producer will reply to all requests starting with /prefix
-  producerHelper.SetPrefix ("/prefix");
+  producerHelper.SetPrefix ("/");
+  producerHelper.SetAttribute ("Postfix", StringValue ("/unique/postfix"));
   producerHelper.SetAttribute ("PayloadSize", StringValue("1024"));
   producerHelper.Install (nodes.Get (2)); // last node