Migrate to ndn-cxx 0.7.1: Part 1

Change-Id: I621a6230272cfde5d84aa5ca9abdf40a91337491
diff --git a/tools/ndncert-ca-server.cpp b/tools/ndncert-ca-server.cpp
index 281e7fe..be0c07d 100644
--- a/tools/ndncert-ca-server.cpp
+++ b/tools/ndncert-ca-server.cpp
@@ -33,7 +33,7 @@
 namespace ndncert {
 
 Face face;
-security::v2::KeyChain keyChain;
+security::KeyChain keyChain;
 std::string repoHost = "localhost";
 std::string repoPort = "7376";