feat(ci): setup GitHub Actions to verify changes

Giving GitHub Actions a shot to see how it
compares to Travis CI.

.github/workflows/verify.yml

@@ -0,0 +1,22 @@
+name: Verify changes
+
+on: [push]
+
+jobs:       
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [4.x, 6.x, 8.x, 10.x, 12.x]
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+      - name: npm install and test
+        run: |
+          npm install
+          npm test