ping: Code refactoring

Change-Id: I8b4e2c9dd3ba3adfae8d296a5635b048b35cf593
Refs: #3137
diff --git a/tools/ping/server/tracer.cpp b/tools/ping/server/tracer.cpp
index fa4e2c8..305fc5d 100644
--- a/tools/ping/server/tracer.cpp
+++ b/tools/ping/server/tracer.cpp
@@ -43,4 +43,4 @@
 
 } // namespace server
 } // namespace ping
-} // namespace ndn
\ No newline at end of file
+} // namespace ndn