Initial cookiecutter

Convert the package template to a cookiecutter, as described in #6 (closed).

Closes: CWG-39

.gitlab-ci.yml

 include:
-- local: "./{{cookiecutter.project_slug}}/.gitlab-ci.yml"
+- local: "{{cookiecutter.project_slug}}/.gitlab-ci.yml"
 
 default:
   before_script: