Add initial CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,18 @@
+name: ci
+on: [push, pull_request]
+jobs:
+  build:
+    name: lint and test
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [8.x, 10.x, 12.x]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+      - run: npm install
+      - run: npm run lint
+      - run: npm test