Add GitLab CI config

.gitlab-ci.yml

+variables:
+  GIT_SUBMODULE_STRATEGY: recursive
+
+pages:
+  stage: deploy
+  script:
+    - mkdir .public
+    - cp -r * .public
+    - rm .public/deploy.py
+    - mv .public public
+  artifacts:
+    paths:
+      - public
+  only:
+    - master