Added GitLab, BitBucket and GitHub CI configurations.

.github/workflows/gradle.yml

@@ -0,0 +1,21 @@
+name: Java CI with Gradle
+
+on: [push, pull_request, workflow_dispatch]
+
+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: Grant execute permission for gradlew
+        run: chmod +x gradlew
+      - name: Test with Gradle
+        run: ./gradlew check
+        env:
+          AKISMET_BLOG: ${{ secrets.AKISMET_BLOG }}
+          AKISMET_API_KEY: ${{ secrets.AKISMET_API_KEY }}