Merge branch 'enable-ci' into 'master'

Enable GitLab's CI

See merge request !1
2 jobs for master in 55 seconds
Status Name Job ID Coverage
  Test
failed test:manifest #53745687

00:00:44

passed test:pep8 #53745688

00:00:55

 
Name Stage Failure
failed
test:manifest Test
lists of files in version control and sdist do not match!
missing from sdist:
.gitlab-ci.yml
suggested MANIFEST.in rules:
include *.yml
ERROR: InvocationError: '/builds/dirn/stonestyle/.tox/manifest/bin/check-manifest'
___________________________________ summary ____________________________________
ERROR: manifest: commands failed
ERROR: Job failed: exit code 1