Add new file

.gitlab-ci.yml

+build_image:
+  image: docker:git
+  services:
+    - docker:dind
+  script:
+    - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY
+    - docker build -t $CI_REGISTRY_IMAGE --pull .
+    - docker push $CI_REGISTRY_IMAGE