model+test: Fixing tests and making sure all tests pass

Refs #1005 (http://redmine.named-data.net/)
diff --git a/model/ndn-interest.cc b/model/ndn-interest.cc
index bd8784e..ffcaa0d 100644
--- a/model/ndn-interest.cc
+++ b/model/ndn-interest.cc
@@ -134,6 +134,7 @@
 Interest::SetPayload (Ptr<Packet> payload)
 {
   m_payload = payload;
+  m_wire = 0;
 }
 
 Ptr<const Packet>