model: Major API changes

Interest and ContentObject are no longer derived from Header class.
Instead, they are encapsulating payload and, optionally, wire-formatted
Packet object.

Refs #1005 (http://redmine.named-data.net/)
diff --git a/model/fw/flooding.cc b/model/fw/flooding.cc
index 3672b24..3d93248 100644
--- a/model/fw/flooding.cc
+++ b/model/fw/flooding.cc
@@ -66,8 +66,7 @@
 
 bool
 Flooding::DoPropagateInterest (Ptr<Face> inFace,
-                               Ptr<const Interest> header,
-                               Ptr<const Packet> origPacket,
+                               Ptr<const Interest> interest,
                                Ptr<pit::Entry> pitEntry)
 {
   NS_LOG_FUNCTION (this);
@@ -80,7 +79,7 @@
       if (metricFace.GetStatus () == fib::FaceMetric::NDN_FIB_RED) // all non-read faces are in the front of the list
         break;
 
-      if (!TrySendOutInterest (inFace, metricFace.GetFace (), header, origPacket, pitEntry))
+      if (!TrySendOutInterest (inFace, metricFace.GetFace (), interest, pitEntry))
         {
           continue;
         }