title: CORS issue with using localhost:3000 to access graphql API at a different URL
body: <p>I have searched all over StackOverflow and saw similar questions but have not found a working solution. Wondering if anyone has a working solution?  I am developing a create react app on localhost:3000 and trying to access through my Apollo Client a URI on a different site (I am testing with <a href="https://developer.github.com/v4/explorer/" rel="noreferrer">https://developer.github.com/v4/explorer/</a>).</p>
  <p>I have added the fetchOptions mode of 'no-cors' to my new ApolloClient instance but I am still getting a CORS error in my console.  My enitre index.js file is below:</p>
  <pre class="lang-js prettyprint-override"><code>import React from 'react';
  import ReactDOM from 'react-dom';
  
  import { ApolloProvider } from 'react-apollo';
  import { ApolloClient, HttpLink, InMemoryCache } from 'apollo-boost';
  
  import './index.css';
  import App from './App';
  import * as serviceWorker from './serviceWorker';
  
  
  const client = new ApolloClient({
      link: new HttpLink({ uri: 'https://developer.github.com/v4/explorer/' }),
      fetchOptions: {
          mode: 'no-cors',
        },
      cache: new InMemoryCache()
    });
    
    const AppWithProvider = () =&gt; (
      &lt;ApolloProvider client={client}&gt;
        &lt;App /&gt;
      &lt;/ApolloProvider&gt;
    );
  ReactDOM.render(&lt;AppWithProvider /&gt;, document.getElementById('root'));
  
  
  serviceWorker.unregister();
  </code></pre>
  <p>Error message in console:
  Access to fetch at 'https://developer.github.com/v4/explorer/' from origin 'http://localhost:3000' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.</p>