Split image building from bind9 project into a separate /images project

.gitignore

+*~
+*.bak

.gitlab-ci.yml

+variables:
+  DEBIAN_FRONTEND: noninteractive
+  LC_ALL: C
+  DOCKER_DRIVER: overlay2
+
+stages:
+  - build
+
+.image: &image
+  image: docker:latest
+  stage: build
+  services:
+    - docker:dind
+  tags:
+    - docker
+  before_script:
+    - docker info
+  script:
+    - docker login -u "$CI_REGISTRY_USER" -p "$CI_JOB_TOKEN" "$CI_REGISTRY"
+    - docker pull "$CI_REGISTRY_IMAGE/$CI_JOB_NAME" || true
+    - docker build --cache-from "$CI_REGISTRY_IMAGE/$CI_JOB_NAME" -t "$CI_REGISTRY_IMAGE/$CI_JOB_NAME" "contrib/docker/$CI_JOB_NAME"
+    - docker push "$CI_REGISTRY_IMAGE/$CI_JOB_NAME"
+  only:
+    - master
+    - triggers
+    - tags
+
+bind9/debian-amd64:oldstable:
+  <<: *image
+
+bind9/debian-i386:oldstable:
+  <<: *image
+
+bind9/debian-amd64:stable:
+  <<: *image
+
+bind9/debian-i386:stable:
+  <<: *image
+
+bind9/debian-amd64:unstable:
+  <<: *image
+
+bind9/debian-i386:unstable:
+  <<: *image
+
+bind9/ubuntu-amd64:latest:
+  <<: *image
+
+bind9/ubuntu-i386:latest:
+  <<: *image
+
+#centos-amd64:latest:
+#  <<: *image
+
+#fedora-amd64:latest:
+#  <<: *image