Merge branch 'docker-in-docker-test' into 'master'

Enable Docker for all stages correctly

See merge request vmchecker/vmchecker-next-assignment!1

.gitlab-ci.yml

@@ -8,6 +8,9 @@ stages:
 
 variables:
   CONTAINER_RELEASE_IMAGE: $CI_REGISTRY_IMAGE:latest
+  DOCKER_HOST: tcp://docker:2375
+  DOCKER_TLS_CERTDIR: ""
+
 
 build:
   stage: build