model+helper+examples: Enable configurability of NFD parameters using StackHelper

Refs: #2353, #2220
diff --git a/examples/ndn-congestion-alt-topo-plugin.cpp b/examples/ndn-congestion-alt-topo-plugin.cpp
index f79bf5d..db0afc7 100644
--- a/examples/ndn-congestion-alt-topo-plugin.cpp
+++ b/examples/ndn-congestion-alt-topo-plugin.cpp
@@ -69,9 +69,8 @@
 
   // Install NDN stack on all nodes
   ndn::StackHelper ndnHelper;
-  ndnHelper.SetContentStoreChoice(false);
-  ndnHelper.SetContentStore("ns3::ndn::cs::Lru", "MaxSize",
-                            "1"); // ! Attention ! If set to 0, then MaxSize is infinite
+  ndnHelper.SetOldContentStore("ns3::ndn::cs::Lru", "MaxSize",
+                               "1"); // ! Attention ! If set to 0, then MaxSize is infinite
   ndnHelper.InstallAll();
 
   // Set BestRoute strategy