Enable NTP sync between compbox deployments

[PeterJCLaw]

We have NTP between the displays in the venue and the compbox, however for various reasons some viewers look at the public compbox. It would be great if the various deployments could be in sync together too.

[PeterJCLaw]

Now that the main class is parametrised (a237a96) this might be more possible. It likely still requires knowing the "other" compbox name(s) somehow though.