Pid-pendulum

Please refer to the documentation in `docs/` for more information.

See `README.md` and documentation in `docs/` for an up-to-date feature list.

With this release, `pip PID-pendulum` works. A basic web app demonstrates the features of the pendulum while utilizing the API. We went from `0.0.1` to `0.0.9` because of PyPI's versioning policy. The intermediate versions should *not* be installed.

The pendulum controller works well and can be installed as a package using `make all`. The API is rudimentary and will be improved in the future. At this point, `GET` requests to the API endpoint yield function values and support values of a pendulum in `JSON` format. Additional information can be found in the installable documentation (`make <doc_format>`) and the `README.md` file.