actions: Move tests to Github Actions

This commit is to move tests from travis CI to Github Actions.

.github/workflows/tests.yml

@@ -0,0 +1,28 @@
+name: tests
+on: [pull_request]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [4.x, 6.x, 8.x, 10.x]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup with Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+      - name: Cache Node.js modules
+        uses: actions/cache@v2
+        with:
+          path: ~/.npm
+          key: ${{ runner.OS }}-node-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.OS }}-node-
+            ${{ runner.OS }}-
+      - name: Install dependencies
+        run:  npm install grunt-cli
+      - name: "Build dist files"
+        run: grunt build
+      - name: "Run tests"
+        run: npm test