Make CKEditor prevent caching images in browsers

[Jakub Ś]

To reproduce:

1. For simplicity use CKEditor with CKFinder.
2. In CKEditor click Image button and then Browse Server button
3. With CKFinder upload image with name abc.jpg, select it and click OK to insert it into CKEditor.
4. In CKEditor, click on the image, next right click on it and choose image properties dialog.
5. Click Browse Server button again
6. While in CKFinder - delete edited image and upload different image with the same name abc.jpg
7. Double click on this image and the click OK to insert it into CKEditor.

Problem: In CKFinder images are refreshed but in CKEditor old image is seen in preview and in CKEditor content area.

1. One solution might be using no-cache HTTP headers on server-side
2. Second is adding some random timestamp parameter behind image name in URL filed of image dialog E.g. abc.jpg?t=1234

The second solution is where editor might come in. It would be nice if CKEditor was doing that in background without any user interaction – perhaps new configuration option could be used here.