Add GitHub Actions workflow for testing

.github/workflows/ci.yml

@@ -0,0 +1,29 @@
+name: Test
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v2
+      with:
+        node-version: ${{ matrix.node-version }}
+    - name: Install NPM v5
+      run: if [[ `npm -v ` != 5* ]]; then npm i -g npm@5; fi
+    - name: Install Dependencies
+      run: npm install
+    - name: Test
+      run: grunt test