Add CI

.gitlab-ci.yml

+image: node:latest 
+
+cache:
+    key: "$CI_BUILD_NAME"
+    paths:
+        - node_modules/
+        - .cache/
+        - latest.tar.gz
+
+before_script:
+    - wget -N https://yarnpkg.com/latest.tar.gz
+    - tar zxf latest.tar.gz
+    - mv dist /opt/
+    - export PATH="/opt/dist/bin:$PATH"
+    - yarn config set cache-folder .cache
+    - yarn install
+
+stages:
+    - lint
+    - test
+
+eslint: 
+    stage: lint
+    script: 
+        - yarn lint
+
+jest:
+    stage: test
+    script:
+        - yarn test