- Run tests from Tox, use generated environments.

- Run tests in TravisCI on multiple Ansible, Python versions and OSes.
- Create Docker container with Ansible.
- Split tests to seperate files.
- Moved everything test related to tests/ .
- Update pre-commit hooks.
- Merge .flake8 to tox.ini.
- Added shellcheck hook.
- Fixed issues found by shellcheck.
- Updated README (added usage, testing sections).