Add Github Actions for CI

Author: rgomezcasas

.github/workflows/gradle.yml

@@ -0,0 +1,20 @@
+name: Java CI
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+    - name: Assemble
+      run: ./gradlew assemble --warning-mode all
+    - name: Check
+      run: ./gradlew check --warning-mode all
+