NFD+model+apps+helper+tests: Upgrade NFD and related changes

Based on NFD:commit:2fc649bfc67b93b4191cfbee5bcd70330bfb48f0 (version 0.3.4)

Change-Id: I89f5182600467171797af4f8f83e1edffe14ad95
Refs: #3125
diff --git a/model/ndn-app-face.cpp b/model/ndn-app-face.cpp
index 1488dff..61c3c21 100644
--- a/model/ndn-app-face.cpp
+++ b/model/ndn-app-face.cpp
@@ -58,7 +58,7 @@
 {
   NS_LOG_FUNCTION(this << &interest);
 
-  this->onSendInterest(interest);
+  this->emitSignal(onSendInterest, interest);
 
   // to decouple callbacks
   Simulator::ScheduleNow(&App::OnInterest, m_app, interest.shared_from_this());
@@ -69,11 +69,23 @@
 {
   NS_LOG_FUNCTION(this << &data);
 
-  this->onSendData(data);
+  this->emitSignal(onSendData, data);
 
   // to decouple callbacks
   Simulator::ScheduleNow(&App::OnData, m_app, data.shared_from_this());
 }
 
+void
+AppFace::onReceiveInterest(const Interest& interest)
+{
+  this->emitSignal(onReceiveInterest, interest);
+}
+
+void
+AppFace::onReceiveData(const Data& data)
+{
+  this->emitSignal(onReceiveData, data);
+}
+
 } // namespace ndn
 } // namespace ns3