Added basic GitHub Actions workflow to build the project

.github/workflows/main.yml

@@ -0,0 +1,15 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    - uses: actions/checkout@v1
+    - name: Use Node.js 8
+      uses: actions/setup-node@v1
+      with:
+        node-version: 8
+    - name: "npm install"
+      run: npm install
+    - name: "Run Grunt"
+      run: grunt