Add gitlab CI config file

see https://docs.gitlab.com/ee/ci/yaml

* Add dependency stage
* Use stretch image instead of alpine
* Add nodejs dependencies
* Add custom project dir (see XXX sections)
2 jobs for feature/gitlab-ci in 15 minutes and 12 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #38
running unit tests

00:07:49

 
  Package
passed #39
build update package

00:07:22