Rename 'src' directory to 'ndn-cxx'

Change-Id: I14394023680901a86977313ca87fb017333614dd
Refs: #3084
diff --git a/examples/producer.cpp b/examples/producer.cpp
index 656ed12..4544ec0 100644
--- a/examples/producer.cpp
+++ b/examples/producer.cpp
@@ -21,11 +21,8 @@
  * @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
  */
 
-// correct way to include ndn-cxx headers
-// #include <ndn-cxx/face.hpp>
-// #include <ndn-cxx/security/key-chain.hpp>
-#include "face.hpp"
-#include "security/key-chain.hpp"
+#include <ndn-cxx/face.hpp>
+#include <ndn-cxx/security/key-chain.hpp>
 
 #include <iostream>