Update postinst file to follow v2 security elements

Change-Id: I17e11e05043ba864052419604096e72a6238ec9c
diff --git a/repo-ng/debian/repo-ng.postinst b/repo-ng/debian/repo-ng.postinst
index d64684a..b49473c 100644
--- a/repo-ng/debian/repo-ng.postinst
+++ b/repo-ng/debian/repo-ng.postinst
@@ -6,7 +6,7 @@
 
 APP=repo-ng
 
-if [ ! -f /var/lib/ndn/$APP/.ndn/ndnsec-public-info.db ]; then
+if [ ! -f /var/lib/ndn/$APP/.ndn/pib.db ]; then
     # Create HOME and generate self-signed NDN certificate
     sudo mkdir -p /var/lib/ndn/$APP/.ndn
     sudo chown -R ndn:ndn /var/lib/ndn/$APP