Hub notifications to gateways on hub changes

[stonier]

Right now every gateway polls the hub looking for changes (in its watcher.py thread) on the hub. It would be much more efficient having one hub watchdog polling for changes and then notifying the interested gateway when there is a delta.

i.e. 1 x polling hub watchdog script is much better than 10-100 polling gateways

This is not a change we immediately require, but worth keeping in mind if we want to redesign/really optimise it for a particular use case.