BZ #1154785: Ensure Public API subnet has a default gateway

https://bugzilla.redhat.com/show_bug.cgi?id=1154785

The public API subnet must have a default gw set. This ensures that
the public API type cannot be assigned to a subnet with the defgw.

(cherry picked from commit adbdc25df46d9137e5cd69d196dcd4b7126cd80c)
Fix version specific deface erb tag

fixes BZ #1154745

(cherry picked from commit db96ed9c16b23ac941cacd1ce771b69572a86102)
Version 0.4.8