Add GA workflow

.github/workflows/default.yml

@@ -0,0 +1,19 @@
+name: Build project
+
+on: [push, pull_request]ó
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: set up JDK 1.8
+        uses: actions/setup-java@v1
+        with:
+          java-version: 1.8
+      - name: Cache .gradle
+        uses: burrunan/gradle-cache-action@v1
+        with:
+          job-id: build
+      - name: Assemble
+        run: ./gradlew assembleDebug --stacktrace