title: setting request headers in selenium
body: <p>I'm attempting to set the request header 'Referer' to spoof a request coming from another site. We need the ability test that a specific referrer is used, which returns a specific form to the user, otherwise an alternative form is given.</p>
  
  <p>I can do this within poltergeist by:</p>
  
  <pre><code>page.driver.headers = {"Referer" =&gt; referer_string}
  </code></pre>
  
  <p>but I can't find the equivalent functionality for the selemium driver.</p>
  
  <p>How can I set request headers in the capybara selenium driver?</p>