src: Changing namespace ndn to namespace nfd

Also, this commit imports used classes from ::ndn namespace (from
NDN-CPP library) directly to ::nfd namespace.

refs: #1163

Change-Id: I9cc9d72e00af495b4ed0c84e6d418a7c9ba986cb
diff --git a/daemon/face/tcp-face.hpp b/daemon/face/tcp-face.hpp
index 3d2bb53..c76cbc8 100644
--- a/daemon/face/tcp-face.hpp
+++ b/daemon/face/tcp-face.hpp
@@ -9,7 +9,7 @@
 
 #include "stream-face.hpp"
 
-namespace ndn
+namespace nfd
 {
 
 /**
@@ -32,6 +32,6 @@
   sendData(const Data& data);
 };
 
-} // namespace ndn
+} // namespace nfd
 
 #endif // NFD_FACE_TCP_FACE_HPP