Set default schema epoch in iptables formula

Schema epoch was not set in defaults (map.jinja).
There is only one schema at the moment (version 1) so
there is no point to not define it in defaults.

Change-Id: Ib75685d1014646daf85280916ac4423388b50c74
diff --git a/iptables/map.jinja b/iptables/map.jinja
index 8ad45f6..1da1b62 100644
--- a/iptables/map.jinja
+++ b/iptables/map.jinja
@@ -1,5 +1,6 @@
 {% set schema = salt['grains.filter_by']({
     'default': {
+        'epoch': 1,
     },
 }, grain='os_family', merge=salt['pillar.get']('iptables:schema')) %}