Now we have 3 configuration levels: common (new!), group and project. And you can run gitlabform with all projects your access token allows. This way it's possible to configure things for all projects in your GitLab instance. See updated config.yaml for examples.
Note: the cli api has changed - ALL now means all projects you have access to, while ALL_DEFINED means, well, all projects and groups defined in the config. This is safe though because if you only upgrade gitlabform without updating the config you will not have the new common_config: key and no new projects will be configured.