all: avoid usage of deprecated namespace ndn::Tlv

refs #2079

Change-Id: I32b7f10bcde1e70617950900d54f6ce0fb588ce9
diff --git a/src/repo-tlv.hpp b/src/repo-tlv.hpp
index bdc3310..45a6a0f 100644
--- a/src/repo-tlv.hpp
+++ b/src/repo-tlv.hpp
@@ -25,7 +25,7 @@
 namespace repo {
 namespace tlv {
 
-using namespace ndn::Tlv;
+using namespace ndn::tlv;
 
 enum {
   RepoCommandParameter = 201,