try fix travis

.travis.yml

     - PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools
     - YARN_CACHE=$HOME/.yarn-cache
     - CODE_SIGNING_REQUIRED=NO
+    - RCT_NO_LAUNCH_PACKAGER=true
 
 branches:
   only:

scripts/clean.js

 run();
 
 function run() {
-  exec.kill('8081');
+  exec.execSync('lsof -t -i tcp:8081 | xargs kill || true');
   exec.execSync(`watchman watch-del-all || true`);
   exec.execSync(`adb reverse tcp:8081 tcp:8081 || true`);
   exec.execSync(`rm -rf lib/ios/DerivedData/`);