PyNDN: Initial changes of PyNDN emulation in ndnSIM

The biggest problem so far, which I cannot solve at all, is exception
handling.  NDN.cxx throws many exceptions when something bad happens,
with are not handled by python bindings

Refs #1008 (http://redmine.named-data.net/issues/1008)
Refs #1011 (http://redmine.named-data.net/issues/1011)
diff --git a/model/ndn-interest.h b/model/ndn-interest.h
index d0959a9..16e8fc3 100644
--- a/model/ndn-interest.h
+++ b/model/ndn-interest.h
@@ -229,6 +229,13 @@
   mutable Ptr<const Packet> m_wire;
 };
 
+inline std::ostream &
+operator << (std::ostream &os, const Interest &i)
+{
+  i.Print (os);
+  return os;
+}
+
 inline Ptr<const Packet>
 Interest::GetWire () const
 {