encoding: Move oid support from security/certificate to encoding.
diff --git a/include/ndn-cpp/security/certificate/public-key.hpp b/include/ndn-cpp/security/certificate/public-key.hpp
index 7db3f49..fa8724f 100644
--- a/include/ndn-cpp/security/certificate/public-key.hpp
+++ b/include/ndn-cpp/security/certificate/public-key.hpp
@@ -10,7 +10,7 @@
 #define	NDN_PUBLIC_KEY_HPP
 
 #include "../../util/blob.hpp"
-#include "oid.hpp"
+#include "../../encoding/oid.hpp"
 #include "../security-common.hpp"
 
 namespace ndn {