Adafruit-circuitpython-hcsr04

We have upgraded Pylint checks to use the latest version of Pylint and implemented usage of Black Python formatting. This does not change the functionality of the code - it is designed to bring it up to current standards and make it more readable.

* Remove pinned Pylint version number from build.yml file
* Synced `.pylintrc` file to match Adafruit standard
* Ran upgraded Pylint and applied any changes or new disables necessary
* Ran Black formatter and allowed application of changes across entire repo

For more information on using Pylint and Black on your code, check out [this guide on working with Pylint and Black](https://learn.adafruit.com/improve-your-code-with-pylint)

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-hcsr04`.

Read the [docs](http://circuitpython.readthedocs.io/projects/hcsr04/en/latest/) for info on how to use it.

This release includes:
* Fixed a section in the README was not allowing PyPI to render it properly.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-hcsr04`.

Read the [docs](http://circuitpython.readthedocs.io/projects/hcsr04/en/latest/) for info on how to use it.

This release includes:
* Some example code in the `README` had incorrect library names. This has been fixed
* Migrating this repository from Travis to GitHub Actions. This has no effect on the behavior of the code itself.

To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://circuitpython.org/libraries).

To use in CPython, `pip3 install adafruit-circuitpython-hcsr04`.

Read the [docs](http://circuitpython.readthedocs.io/projects/hcsr04/en/latest/) for info on how to use it.

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

To use in CPython, `pip3 install adafruit-circuitpython-hcsr04`.

Read the [docs](http://circuitpython.readthedocs.io/projects/hcsr04/en/latest/) for info on how to use it.

- 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-hcsr04`.

Read the [docs](http://circuitpython.readthedocs.io/projects/hcsr04/en/latest/) for info on how to use it.

Updated docs and semver versioning.

To use in CircuitPython, download the .mpy file and copy it to the `lib` folder on the `CIRCUITPY` drive. Or, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).

Read the [docs](http://circuitpython.readthedocs.io/projects/hcsr04/en/latest/) for info on how to use it.