replace gitlab ci with drone

.drone.yml

@@ -0,0 +1,15 @@
+pipeline:
+  docker:
+    image: plugins/docker
+    repo: registry.gitlab.com/thallian/docker-roundcube
+    registry: registry.gitlab.com
+    autotag: true
+    secrets: [ docker_username, docker_password ]
+    tags:
+    - ${DRONE_COMMIT_SHA}
+    - ${DRONE_COMMIT_BRANCH}
+    - latest
+  notify:
+    image: plugins/matrix
+    secrets: [ matrix_username, matrix_password, matrix_homeserver, matrix_roomid ]     
+

.gitlab-ci.yml

@@ -1,10 +0,0 @@
-build:
-   image: docker:latest
-   services:
-   - docker:dind
-   stage: build
-   script:
-     - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
-     - docker build --pull --tag $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME --tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA .
-     - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME
-     - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA