Physical capacitive touch: Reset and sensitivity control

[andrewn]

This adds support for some more advanced features of the capacitive touch board.

Reset (92032571354edfc5c0af4579ad73c9865bbce0a5)

Resetting the board re-calibrates the sensors which is very useful when moving wires.

Capacitive/:id/resetRequest will perform the reset. Capacitive/:id/reset is emitted when a reset occurs.

Getting/setting sensitivity (982e125a81fcd6bd3cbeef5ee5207adae834c72b)

Allows an app to change how sensitive the board is to touches.

Capacitive/:id/statusRequest request the sensitivity. Capacitive/:id/status emits a payload of { sensitivity: NUMBER }

To change the sensitivity send, Capacitive/:id/sensitivity with a payload { params: { level: NUMBER } }. Capacitive/:id/status is emitted when the sensitivity changes.

Message routing

~As discussed, it'd be nice to have some library support and some naming conventions and patterns for this stuff to apply across the services and apps. I like the patterrn of being able to send a command to a service (e.g. sensitivity) and know that it has been executed, or failed with an error. But also for other parts of the system to listen for events (status).~

This has been re-based onto the new WebSocket library from #40.

[pixelblend]

I just remembered that for the Radiodan Server we used Commands and Events as a way to split the request / response topics up. Do we want to do that again here?

[andrewn]

I think that makes a lot of sense, and will be easier to understand than RPC and Pub/Sub.

[andrewn]

@pixelblend Are you happy for me to merge this? I can do another PR that converts all of the physical service to use command/event naming patterns.