Add certificate fetcher of ndns-appcert and ndns-cert

Validators are updated accordingly

Change-Id: Ibdee00b8f20243448a2ba3011ca87f85ce1ea516
diff --git a/tests/unit/daemon/name-server.cpp b/tests/unit/daemon/name-server.cpp
index 707ff95..a8dbd3b 100644
--- a/tests/unit/daemon/name-server.cpp
+++ b/tests/unit/daemon/name-server.cpp
@@ -44,6 +44,7 @@
   {
     // ensure prefix is registered
     run();
+    advanceClocks(time::milliseconds(10), 1);
   }
 
   void