Standardization

Fix documentation and tag format

CI sync

CI: deploy image to dockerhub when tagging

Also re-join workflows.

Pin ruby

• Pin ruby to 2
• Use *.deb if possible, only search subdirs if that doesn't work

v0.1: Basic test implementation

- README.md
- Dockerfile based on ruby:alpine, installing package_cloud script
- entrypoint and action.yml to test
- github action workflow with omnilint and docker build