Add gitlab ci template which can be used by all Ansible inventory projects

.gitlab-ci-template.yml

+stages:
+  - build
+  - deploy
+
+before_script:
+  - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
+
+build-docker-image:
+  stage: build
+  script:
+    - docker build --pull -t "$CI_REGISTRY_IMAGE" .
+    - docker push "$CI_REGISTRY_IMAGE"
+  only:
+    - master
+    - chat
+
+update-docker-image:
+  stage: deploy
+  tags:
+    - ansible-update
+  variables:
+    GIT_STRATEGY: none
+  script:
+    - docker pull "$CI_REGISTRY_IMAGE"
+  only:
+    - master
+    - chat