model: Slight modification with wire format processing

Now it is possible to convert Name from/to wire format via ndn::Face
helper method (since Face is getting configured with specific wire
format)

Refs #1008 (http://redmine.named-data.net/issues/1008)
diff --git a/model/ndn-interest.cc b/model/ndn-interest.cc
index 134cd01..7364701 100644
--- a/model/ndn-interest.cc
+++ b/model/ndn-interest.cc
@@ -55,6 +55,17 @@
 {
 }
 
+Interest::Interest (Ptr<const Interest> interest)
+  : m_name             (Create<Name> (interest->GetName ()))
+  , m_scope            (interest->m_scope)
+  , m_interestLifetime (interest->m_interestLifetime)
+  , m_nonce            (interest->m_nonce)
+  , m_nackType         (interest->m_nackType)
+  , m_payload          (interest->GetPayload ()->Copy ())
+  , m_wire             (0)
+{
+}
+
 void
 Interest::SetName (Ptr<Name> name)
 {