Moving iptables rules to the relevant elements

This patch moves the iptables rules from elements/boot-stack to
an os-refresh-config/pre-configure.d directory within the element
that is relevant to the rule.
This patch relies on the add-rule script.

Change-Id: Idf0eca03f104829896b07693f1f22f31270c91c5
Merge "Moving iptables rules to the relevant elements"