bootstrap package setup via cookiecutter
Based on template from https://github.com/audreyr/cookiecutter-pypackage
Changes from default template:
* unpin dev requirements for now
* rm 'watchdog' dev requirement and remove use
from Makefile
* sort requirements_dev, unpin and note bumpversion
* Use 'Apache-2.0' spdx.org style licence identifier to match ansible/galaxy/setup.py.
* rm docs from sdist
* mv rst docs to docs/rst
* add .pytest_cache to gitignore
