Start Github actions

.github/workflows/build.yml

@@ -0,0 +1,17 @@
+name: build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK 8
+      uses: actions/setup-java@v2
+      with:
+        java-version: '8'
+        distribution: 'adopt'
+    - name: Build with Gradle
+      run: gradle build