plugins/ip-faces: Updating TcpFace implementation

In addition to changes to follow latest API changes in ndnSIM, the
helper ndn::IpFacesHelper allows scheduling TcpFace creation at specific
point of simulation.

Refs #1006 (http://redmine.named-data.net/)
diff --git a/examples/ndn-simple-tcp.cc b/examples/ndn-simple-tcp.cc
index 641348a..f959dc7 100644
--- a/examples/ndn-simple-tcp.cc
+++ b/examples/ndn-simple-tcp.cc
@@ -97,9 +97,8 @@
                        Ipv4Address ("10.1.2.1"),
                        1, 1);
   
-  ndn::IpFacesHelper ipFacesHelper;
-  ipFacesHelper.InstallAll ();
-  ipFacesHelper.CreateTcpFace (nodes.Get (0), Ipv4Address ("10.1.2.2"), "/tcp-route");
+  ndn::IpFacesHelper::InstallAll ();
+  ndn::IpFacesHelper::CreateTcpFace (Seconds (1.0), nodes.Get (0), Ipv4Address ("10.1.2.2"), "/tcp-route");
   
   // Installing applications