Adafruit-circuitpython-l3gd20

- Added `setup.py`
- Added PyPI release info to `.travis.yml`
- Updated `requirements.txt`
- Added a more comprehensive `.gitignore`

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

To use in CPython, `pip install adafruit-circuitpython-l3gd20`.

Read the [docs](http://circuitpython.readthedocs.io/projects/l3gd30/en/latest/) for info on how to use it.

Release includes:

- Updates to Read The Docs

- Added default `range` value when initializing, and `range` argument checking.


Thanks mrmcwethy for the updates!

Adafruit_CIrcuitPython_L3GD20