Add dependencies for ubuntu

Bifrost sets up iptables rules. Especially in container
environments this package may be missing, so bifrost should
install it as a requirement.
Additionally iscsi deployments rely on hexdump, which is part of
bsdmainutils, which may be missing as well.

Change-Id: I2fe16e572ff0705248d842d93ea178bf0f8b35b4

playbooks/roles/bifrost-ironic-install/defaults/required_defaults_Ubuntu_16.04.yml

@@ -16,6 +16,8 @@ required_packages:
   - tftp-hpa
   - xinetd
   - parted
+  - iptables
+  - bsdmainutils
   - ipmitool
   - psmisc
   - nginx

playbooks/roles/bifrost-ironic-install/defaults/required_defaults_Ubuntu_18.04.yml

@@ -17,6 +17,8 @@ required_packages:
   - xinetd
   - parted
   - ipmitool
+  - iptables
+  - bsdmainutils
   - psmisc
   - nginx
   - wget