Fix travis build

.travis.yml

@@ -1,5 +1,5 @@
 language: android
-sudo: false
+sudo: required
 jdk: oraclejdk8
 env:
   matrix:
@@ -7,14 +7,23 @@ env:
 android:
   components:
     - tools # https://github.com/travis-ci/travis-ci/issues/5049
+    - tools # https://github.com/travis-ci/travis-ci/issues/6040
     - android-24
-    - platform-tools-24.0.2
+    - platform-tools
     - build-tools-24.0.2
     - extra-android-m2repository
     - extra-google-m2repository
   licenses:
     - 'android-sdk-license-.+'
 
+before_cache:
+  - rm -f $HOME/.gradle/caches/modules-2/modules-2.lock
+
+cache:
+  directories:
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
+
 before_install:
   - echo no | android create avd --force -n test -t $ANDROID_TARGET --abi $ANDROID_ABI
   - emulator -avd test -no-skin -no-audio -no-window &