Added `setuptools-scm` as a build system requirement to fix dynamic dependencies.
To use in CircuitPython, simply install the [Adafruit CircuitPython Bundle](https://circuitpython.org/libraries).
To use in CPython, `pip3 install adafruit-circuitpython-neopixel`.
Read the [docs](http://circuitpython.readthedocs.io/projects/neopixel/en/latest/) for info on how to use it.