title: .eslintignore is ignored by create-react-app?
body: <p>I've placed a <code>.eslintignore</code> file in the root of my create-react-app installation, so I can ignore warnings from vendor libs.</p>
  
  <p>It works fine if I run eslint from the commandline:</p>
  
  <pre><code>./node_modules/.bin/eslint src/js/vendor/jquery.js
  ...warnings ignored...
  </code></pre>
  
  <p>However running <code>npm start</code> and <code>npm run build</code> seem to ignore the ignore file.</p>
  
  <p>How can I achieve what I want to do here - without editing individual vendor files to add eslint options?</p>