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 }}

.gitlab-ci.yml

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+image: gradle:alpine
+
+variables:
+  GRADLE_OPTS: "-Dorg.gradle.daemon=false"
+
+before_script:
+  - export GRADLE_USER_HOME=`pwd`/.gradle
+
+stages:
+  - build
+  - test
+
+build:
+  stage: build
+  script: ./gradlew --build-cache assemble
+  cache:
+    key: "$CI_COMMIT_REF_NAME"
+    policy: push
+    paths:
+      - build
+      - .gradle
+
+test:
+  stage: test
+  script: ./gradlew check
+  cache:
+    key: "$CI_COMMIT_REF_NAME"
+    policy: pull
+    paths:
+      - build
+      - .gradle

bitbucket-pipelines.yml

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+image: openjdk:8
+
+pipelines:
+  default:
+    - step:
+        caches:
+          - gradle
+        script:
+          - bash ./gradlew check