title: Invalid Host header when running Create React App on localhost subdomain
body: <p>After updating to  the react-scripts 1.0.0 I get this error when I try to open my app in the browser on a localhost subdomain: 'Invalid Host header'</p>
  
  <p>My app was set up to serve different data for different subdomains:
  group1.localhost:3000
  group2.localhost:3000
  ...</p>
  
  <p>I found that adding the code below to my webpack config should fix the problem.</p>
  
  <pre><code>devServer: {
    disableHostCheck: true
  }
  </code></pre>
  
  <p>But how can i fix it in CRA without ejecting?</p>