title: FileContentResult returned as jpg but IE "Save picture as" only gives png or bmp
body: <p>I have an MVC 4 controller method returning a FileContentResult as follows:</p>
  
  <pre><code>[OutputCache(CacheProfile = "ImageCache")]
  public FileContentResult GetImage(string dl)
  {
      return File(photoSig.BinaryPhoto, "image/jpeg", "photo.jpg");
  }
  </code></pre>
  
  <p>The ImageCache is defined as follows:<br/>
  <code>&lt;caching&gt;
    &lt;outputCacheSettings&gt;
      &lt;outputCacheProfiles&gt;
        &lt;add name="ImageCache" duration="1" varyByParam="*" location="Server" enabled="true" /&gt;
      &lt;/outputCacheProfiles&gt;
    &lt;/outputCacheSettings&gt;
  &lt;/caching&gt;</code></p>
  
  <p>Everything works fine except in IE, when the user does a Save picture as..., it only gives them the option to save as PNG or BMP.  Why wouldn't it by a jpg?  Chrome and FF give the jpg option as it should.</p>
  
  <p>Another interesting point is that it works fine on my local box but not when deployed...which makes me think it could be a configuration issue.  But I don't know where to start looking.  The IIS MIME type for jpg is defined on the UI server.</p>