title: No 'Access-Control-Allow-Origin' over rxjs
body: <p>I've been building up simple react app which shows following crytowat.ch api.
  <a href="https://api.cryptowat.ch/markets" rel="nofollow noreferrer">https://api.cryptowat.ch/markets</a></p>
  
  <p>here is my code for redux-observable Epic</p>
  
  <pre><code>const cryptowatchEpic = action$ =&gt;
  action$.ofType(FETCH_PRICE).mergeMap(action =&gt;
      ajax({
        url: `${baseUrl}${action.payload}/btcusd/price`,
        crossDomain: true,
        method: 'GET',
        headers: {
          'Access-Control-Request-Origin': 'https://api.cryptowat.ch/'
        },
        withCredentials: true
      }).map(response =&gt; fetchPriceFilled(response))
    );
  </code></pre>
  
  <p>and here is console error</p>
  
  <blockquote>
    <p>XMLHttpRequest cannot load <a href="https://api.cryptowat.ch/markets/kraken/btcusd/price" rel="nofollow noreferrer">https://api.cryptowat.ch/markets/kraken/btcusd/price</a>. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '<a href="http://localhost:3000" rel="nofollow noreferrer">http://localhost:3000</a>' is therefore not allowed access. The response had HTTP status code 405.</p>
  </blockquote>
  
  <p>I think passed <code>Access-Control-Request-Origin</code> in headers but i occurs error. is there something i missed?</p>
  
  <p>thanks in advance</p>