Stograde

- Add truncation capability to all types of output (file contents, compile output, test output)
- Add `CONTRIBUTING.md`
- Don't try to read contents of file in `cat()` if they are going to be hidden by output
- Catch `PermissionError`s in `run_static()`
- Refactor formatters to be more readable and have more concise output
- Fix issue with labs not failing CI builds in all classes instead of only Software Design
- Add `docs/REFEREE.md`

- Fix issue with dependencies related to `stograde drive`
- Use `pytest-flake8` instead of `pytest-pep8` for testing PEP8 compliance
- Fix some tests

- Add `stograde drive` support 203
- Add support for `linux/amd64` and `linux/arm/v7` versions of docker images 204 205 206 207 208
- Improve documentation for `stograde ci` 209

- Fix bug with Markdown files not showing tests
- Increase test coverage to 100%
- Remove bidict dependency
- Reincorporate html formatter
- Update gist functionality
- Use GitHub personal access token to authenticate gist instead of password
(Using a password will be deprecated in November 2020 according to [GitHub Documentation](https://docs.github.com/en/rest/overview/other-authentication-methods#via-username-and-password))