Allow user-provided templates

[ancoron]

I need certain modifications to the standard rules, including but not limited to:

• drop ip6tables input rule for NTP
• add ip6tables input rule to allow DHCPv6

And apart from the service-related rules, I'd also like to customize the behavior of the whitelisting by switching from DROP to REJECT.

Therefore, it would be nice to have the option of specifying a custom template file without the need to fork the project.

[DaisyDomergue]

Hi, Thanks for all the ansible roles. I have had the need to use custom templates on this role for so long. Now I have tried to add the feature with a couple of lines change. Hopefully this will help with this feature.