Add gitlab.ci file for CI

.gitlab-ci.yml

+stages:
+  - build
+  - deploy
+
+build_development:
+  stage: build
+  only:
+    - master
+    - sandbox
+  script:
+    - docker-compose --project-name service-email-dev build
+
+deploy_development:
+  stage: deploy
+  only:
+    - master
+    - sandbox
+  script:
+    - docker-compose --project-name service-email-dev up -d
+  environment:
+    name: development
+
+build_staging:
+  stage: build
+  only:
+    - staging
+  script:
+    - docker-compose --project-name service-email-rec build
+
+deploy_staging:
+  stage: deploy
+  only:
+    - staging
+  script:
+    - docker-compose --project-name service-email-rec up -d
+  environment:
+    name: staging