Update Travis build script

Author: kuoruan

.travis.yml

@@ -25,16 +25,19 @@ android:
     - tools
     - build-tools-$ANDROID_BUILD_TOOLS
     - android-$ANDROID_API
-    - extra-android-support
     - extra-google-google_play_services
     - extra-google-m2repository
+    - extra-android-m2repository
   licenses:
-    - '.+'
+    - 'android-sdk-license-.+'
+    - 'android-sdk-preview-license-.+'
+    - 'google-gdk-license-.+'
 
 notifications:
   email: false
 
 before_install:
+  - yes | sdkmanager "platforms;android-27"
   - openssl aes-256-cbc -K $encrypted_fe6090d19007_key -iv $encrypted_fe6090d19007_iv -in chrome.jks.enc -out chrome.jks -d
   - chmod +x gradlew
   - ./gradlew dependencies