ci: use gitlab's review apps (using surge.sh)

Closes #42

.gitlab-ci.yml

@@ -5,6 +5,7 @@ stages:
   - build
   - test
   - docs
+  - deploy
 
 setup:
   image: registry.gitlab.com/openstapps/projectmanagement/builder
@@ -70,3 +71,28 @@ pages:
   artifacts:
     paths:
       - public
+
+review:
+  stage: deploy
+  script:
+    - npm run build:prod
+    - ./node_modules/.bin/surge -p ./www -d https://$CI_PROJECT_PATH_SLUG-$CI_ENVIRONMENT_SLUG.surge.sh/
+  environment:
+    name: review/$CI_PROJECT_PATH_SLUG-$CI_COMMIT_REF_NAME
+    url: https://$CI_PROJECT_PATH_SLUG-$CI_ENVIRONMENT_SLUG.surge.sh/
+    on_stop: stop_review
+  tags:
+    - secrecy
+
+stop_review:
+  stage: deploy
+  variables:
+    GIT_STRATEGY: none
+  script:
+    - ./node_modules/.bin/surge teardown $CI_PROJECT_PATH_SLUG-$CI_ENVIRONMENT_SLUG.surge.sh
+  when: manual
+  environment:
+    name: review/$CI_PROJECT_PATH_SLUG-$CI_COMMIT_REF_NAME
+    action: stop
+  tags:
+    - secrecy