Zigpy

Fixes
- Add a command queue so there is always only one pending command jloehr (112)

Breaking changes

- Drop py35 support Adminiuga (95)

🚀 Features

- Feature/usb reconnect Adminiuga (99)
- Implement radio probe. Adminiuga (101)
- Add black check to travis Adminiuga (96)

Changes

- Add isort Adminiuga (100)
- Add PyPa workflow. Adminiuga (98)
- Refactor DeviceState as an enum.IntFlag Adminiuga (97)
- Create Contributors.md file with list of contributors Hedda (89)
- Added a "How to contribute" section to README.md Hedda (90)

Changes

* Fix firmware download

Fix probing pizigate

- Differentiate input/output (server/client) clusters (https://github.com/zigpy/zigpy/pull/216)

Fixes
- Don't apply quirks second time to a quirked device (https://github.com/zigpy/zigpy/pull/199)