In this pull-request I wanted to introduce valid-response-codes settings, that returns failed result, when response code of webhook is not among the list of valid codes. For goals of backwards compatibility, if this slice of valid-response-codes is empty, check is not performed.
* Use specific plugin versions, pull latest versions and enable a microbadger webhook
* Use the new plugins/base:multiarch image
* Write readme like it is done for other plugins
* Downcase all wording like on other plugins, move variables to correct file
* Added dockerignore file
* Added missing schema version label
* Only execute webhook on master branch
* Added issue and pull request templates
* Added blank line to gitignore
Thomas Boerger