Fix duplicate "update" messages from Services.

Under circumstances I'm unable to duplicate beyond a specific machine
on a specific network, the UdpBroadcast Manager receives duplicate
messages shortly after startup. This caused duplicate events to be
fired from the Registry, breaking the tests and a number of assumptions.

This commit adds a guard against that behaviour.
Make cluster logging test more useful.
Add test for duplicate UDP updates.
Add more unique, immediately-available UdpManager IDs.

Previously, it used the host/port as bound, which are neither unique
nor available immediately. It was a quick solution, but this one
(based on `os.networkInterfaces()` via the `ip` module) is a more
sustainable and accurate solution.