use github actions

.github/workflows/grunt-build.yml

@@ -0,0 +1,35 @@
+name: Build Webapp
+
+on:
+  push:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js
+      uses: actions/setup-node@v1
+      with:
+        node-version: 10.x
+    # https://help.github.com/en/actions/configuring-and-managing-workflows/caching-dependencies-to-speed-up-workflows
+    - name: Cache node modules
+      uses: actions/cache@v2
+      env:
+        cache-name: cache-node-modules
+      with:
+        # npm cache files are stored in `~/.npm` on Linux/macOS
+        path: ~/.npm
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
+        restore-keys: |
+          ${{ runner.os }}-build-${{ env.cache-name }}-
+          ${{ runner.os }}-build-
+          ${{ runner.os }}-
+    - name: Fetch bower
+      run: npm install -g bower grunt-cli
+    - name: npm ci
+      run: npm ci --prefer-offline
+    - name: bower install
+      run: bower install --allow-root
+    - name: Run Build
+      run: grunt build