Compile with the ndn-cxx version 0.6.2

Change-Id: If474dafb9638d7308f566b1264aa5704ba88baac
diff --git a/tools/ndncert-ca-server.cpp b/tools/ndncert-ca-server.cpp
index 9e25555..c666d34 100644
--- a/tools/ndncert-ca-server.cpp
+++ b/tools/ndncert-ca-server.cpp
@@ -105,7 +105,11 @@
             auto issuedCert = request.getCert();
             using namespace boost::asio::ip;
             tcp::iostream requestStream;
+#if BOOST_VERSION >= 106700
+            requestStream.expires_after(std::chrono::seconds(3));
+#else
             requestStream.expires_from_now(boost::posix_time::seconds(3));
+#endif // BOOST_VERSION >= 106700
             requestStream.connect(repoHost, repoPort);
             if (!requestStream) {
               std::cerr << "ERROR: Cannot publish certificate to repo-ng"