Added cache, removed licenses.

.travis.yml

@@ -3,15 +3,17 @@ jdk:
   - oraclejdk8
 
 before_install:
-  - mkdir "$ANDROID_HOME/licenses" || true
-  - echo -e "\n8933bad161af4178b1185d1a37fbf41ea5269c55" > "$ANDROID_HOME/licenses/android-sdk-license"
-  - echo -e "\n84831b9409646a918e30573bab4c9c91346d8abd" > "$ANDROID_HOME/licenses/android-sdk-preview-license"
   - chmod +x gradlew
 
+before_cache:
+  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
+  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
+
 cache:
   directories:
-    -$HOME/.gradle/caches/
-    -$HOME/.gradle/wrapper/
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
+    - $HOME/.android/build-cache
 
 android:
   components:
@@ -27,4 +29,4 @@ android:
     - google-gdk-license-.+
 
 script:
-   - ./gradlew clean build connectedCheck -PdisablePreDex --stacktrace
+  - ./gradlew clean build connectedCheck -PdisablePreDex --stacktrace