* Build feature branches with branch tag
* Build short and long image tag
* Add latest and stable tag, made moving repos easier
* Only push tags to registry
* Only build tags that where changed
* Fix if and quoting, push $VERSION_SHORT
* Update MicroBadger with Webhook, closes#251
* Quote vars
* Set tag on PR, too
* Switch to hadolint docker image
due to PR not having enviroment variables and I don't want to commit my token in the script
* Only push image on master
* Quote all vars, remove useless echo/sub-shell, add shebands, fail on unset vars, enable pipefail, formatting
* Add CI including linting via hadolint nad shellcheck
* Update all base images to tag 3.9
* Switch to maintainer labels
* Quote vars
* Remove commented code
* Ignore if the folder exists
