Add simple .gitlab-ci.yml

- just testing gitlab-ci -> slack posting
6 jobs for master in 49 seconds
Status Name Job ID Coverage
  Build
passed build_Go #664

00:00:33

 
  Test
passed test_Go #666

00:00:16

 
  External
passed jenkins

00:00

passed jenkins

00:00:02

passed jenkins

00:00:02

passed jenkins

00:00:02