Add CI

.github/workflows/android.yml

@@ -0,0 +1,23 @@
+name: Android CI
+# from https://medium.com/@wkrzywiec/github-actions-for-android-first-approach-f616c24aa0f9
+
+on:
+  push:
+    branches:
+      - '*'
+      # - '!master'
+      # - '!release*'
+
+jobs:
+  test:
+    name: Run Unit Tests
+    runs-on: ubuntu-18.04
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+    - name: Unit tests
+      run: bash ./gradlew test --stacktrace