Add conntrack-tools to nova dependencies

'Error deleting conntrack entries' appears in all
n-net. Adding conntrack-tools/conntrack as nova dependency,
in order to eliminate this issue.

Change-Id: Ief9deeb3349a07e22fb365e58f3368c847f845ef
diff --git a/files/rpms-suse/nova b/files/rpms-suse/nova
index 3e95724..7a1160e 100644
--- a/files/rpms-suse/nova
+++ b/files/rpms-suse/nova
@@ -1,6 +1,7 @@
 curl
 dnsmasq
 dnsmasq-utils # dist:opensuse-12.3,opensuse-13.1
+conntrack-tools
 ebtables
 gawk
 genisoimage # required for config_drive