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/core/monotonic_deadline_timer.hpp b/daemon/core/monotonic_deadline_timer.hpp
index 543cd7a..c158fe4 100644
--- a/daemon/core/monotonic_deadline_timer.hpp
+++ b/daemon/core/monotonic_deadline_timer.hpp
@@ -17,15 +17,15 @@
 namespace asio {
 
 template <> 
-struct time_traits<ndn::time::monotonic_clock>
+struct time_traits<nfd::time::monotonic_clock>
 {
-  typedef ndn::time::Point time_type;
-  typedef ndn::time::Duration duration_type;
+  typedef nfd::time::Point time_type;
+  typedef nfd::time::Duration duration_type;
 
   static time_type
   now()
   {
-    return ndn::time::now();
+    return nfd::time::now();
   }
 
   static time_type
@@ -53,7 +53,7 @@
   }
 };
 
-typedef basic_deadline_timer<ndn::time::monotonic_clock> monotonic_deadline_timer; 
+typedef basic_deadline_timer<nfd::time::monotonic_clock> monotonic_deadline_timer; 
 
 } // namespace asio
 } // namespace boost