Update .gitlab-ci.yml

.gitlab-ci.yml

 image: openjdk:8-jdk
 
 variables:
-  ANDROID_COMPILE_SDK: "25"
-  ANDROID_BUILD_TOOLS: "24.0.3"
-  ANDROID_SDK_TOOLS: "25.2.3"
+  GRADLE_VERSION: "2.14.1"
 
 before_script:
-  - wget --quiet --output-document=android-sdk.zip https://dl.google.com/android/repository/tools_r${ANDROID_SDK_TOOLS}-linux.zip
-  - mkdir -p sdk
-  - cd sdk
-  - unzip -o -qq ../android-sdk.zip
-  - echo y | tools/android --silent update sdk --no-ui --all --filter android-${ANDROID_COMPILE_SDK}
-  - echo y | tools/android --silent update sdk --no-ui --all --filter platform-tools
-  - echo y | tools/android --silent update sdk --no-ui --all --filter build-tools-${ANDROID_BUILD_TOOLS}
-  - echo y | tools/android --silent update sdk --no-ui --all --filter extra-android-m2repository
-  - echo y | tools/android --silent update sdk --no-ui --all --filter extra-google-google_play_services
-  - echo y | tools/android --silent update sdk --no-ui --all --filter extra-google-m2repository
-  - cd ..
-  - export ANDROID_HOME=$PWD/sdk
-  - export PATH=$PATH:$PWD/sdk/platform-tools/
-  - gradle wrapper
+  - gradle wrapper --gradle-version ${GRADLE_VERSION} -Dcom.android.build.gradle.overrideVersionCheck=true
 
 stages:
   - build