model: Add ability to print interest to the standard output, so it plays nice with PyNDN

Refs #1010 (http://redmine.named-data.net/issues/1010)
diff --git a/model/ndn-content-object.cc b/model/ndn-content-object.cc
index ecf3197..9df1d27 100644
--- a/model/ndn-content-object.cc
+++ b/model/ndn-content-object.cc
@@ -31,7 +31,8 @@
 namespace ndn {
 
 ContentObject::ContentObject (Ptr<Packet> payload/* = Create<Packet> ()*/)
-  : m_signature (0)
+  : m_name (Create<Name> ())
+  , m_signature (0)
   , m_payload (payload)
   , m_wire (0)
 {