title: Change package name and app name in react native
body: <p>Hi how can I change the package name and the name that will be displayed on the phone in react-native ? I've tried to change the name in app.json and package.json and then delete <code>android</code> and <code>ios</code> folders but when I want to regenerate these folders with <code>react-native upgrade</code> it doesn't work..</p>
  
  <p>Thanks.</p>