title: Use create-react-app behind corporate firewall
body: <p>there is any way for work with <code>create-react-app</code> behind corporate firewall by setting a proxy.</p>
  
  <p>i have setted the proxy on npm and yarn, but this is what i see when try to <code>create-react-app my-app</code>: </p>
  
  <pre><code>Creating a new React app in F:\react\my-app.
  
  Installing packages. This might take a couple of minutes.
  Installing react, react-dom, and react-scripts...
  
  You appear to be offline.
  Falling back to the local Yarn cache.
  
  yarn add v0.23.4
  info No lockfile found.
  [1/4] Resolving packages...
  error Couldn't find any versions for "react" that matches "latest" in our cache. Possible versions: ""
  info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.
  
  Aborting installation.
    yarnpkg add --exact --offline react react-dom react-scripts has failed.
  
  Deleting generated file... package.json
  Deleting my-app / from F:\react
  Done.
  </code></pre>