## Description:
More fixes flagged by pylint 2 that don't hurt to have before the actual pylint 2 upgrade (which I'll submit soon).
## Checklist:
- [ ] The code change is tested and works locally.
- [x] Local tests pass with `tox`. **Your PR cannot be merged unless tests pass**
* make device_discovered synchronous
* small fixes from code review
* use dispatcher to update sensor state
* update switch state based on response from the device
* interpolate entity_id into dispatcher signal
* cleanup lint
* change coroutine to callback
Nate Clark
Ville Skyttä