make repo output the default in systemd file

Change-Id: Ida5d4e988acd79beb4f8ed2249ed83c79bc6419f
diff --git a/systemd/ndncert-ca.service.in b/systemd/ndncert-ca.service.in
index 5ac1a2b..8ab77ac 100644
--- a/systemd/ndncert-ca.service.in
+++ b/systemd/ndncert-ca.service.in
@@ -3,7 +3,7 @@
 
 [Service]
 Environment=HOME=%S/ndncert-ca
-ExecStart=@BINDIR@/ndncert-ca-server
+ExecStart=@BINDIR@/ndncert-ca-server -r
 Restart=on-failure
 RestartPreventExitStatus=2
 User=ndn