[WIP] adds dynamic zone serial generation for bind master

[kylerisse]

Description of PR

Dynamically generate the bind zone serial number based on git commit timestamp

Previous Behavior

• statically set zone serial, caching errors

New Behavior

• ever incrementing zone serial based on timestamp

Tests

Tested on @MatthewCroughan 's nix demo machine

[sarcasticadmin]

cherry-picked via https://github.com/socallinuxexpo/scale-network/pull/576

Thanks @kylerisse for getting this done! Its applied and running now on the core servers :shipit:

[nixinator]

@kylerisse clever girl!