Switch Travis over to gradle

tools/travis/continuous-build.sh

@@ -11,8 +11,7 @@ function main() {
   fi
   export ANDROID_HOME="$(cd ../android; /bin/pwd)"
   export PATH="$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools:$PATH"
-  ./create-build-files.sh
-  ant clean debug
+  ./gradlew clean assembleDebug
 }
 
 set -e

tools/travis/continuous-test.sh

@@ -57,10 +57,9 @@ function main() {
   which emulator || (echo "adb not found"; return 1)
 
   start_emulator
-  cd tests
-  ant clean debug
+  ./gradlew assembleDebug
   wait_for_emulator
-  ant installd test
+  ./gradlew connectedCheck
   pkill emulator
 }