title: Facebook SDK Share Link content gets replaced by meta data from content URL
body: <p>I've set up content for FBSDKShareLinkContent, and set each param contentURL, contentTitle, contentDescription, imageURL. </p>
  
  <p>When the share dialog loads in the facebook native app, it is <strong>correctly populated</strong> with my params.</p>
  
  <p>However, once I check the post on facebook, the param <strong>data is no longer shown</strong> and instead the post title is from the meta data of the contentURL. </p>
  
  <p>How do I override the meta data with my contentDescription and contentTitle? 
  Thanks!</p>
  
  <pre><code>  // Assemble Content
      var content: FBSDKShareLinkContent = FBSDKShareLinkContent()
      content.contentURL =  NSURL(string: DOWNLOAD_LINK_APPSTORE)
      content.contentTitle = "My Custom Title"
      content.contentDescription = "My Custom Description"
      content.imageURL = NSURL(string: FB_IMAGE_LINK)
     // Share Dialog
      FBSDKShareDialog.showFromViewController(self, withContent: content, delegate: nil)
  </code></pre>