Image dialog doesn't display properties set to 0.

[Jakub Ś]

1. Open image dialog
2. Insert URl and set border, hspace and vspace to 0
3. Click OK and switch to source - 0 are present in image styles
4. Switch back to WYSIWYG, right-click on image and choose image properties.

Result: 0 are not displayed in dialog.

Issue has been reproducible from CKEditor 3.1.1.
From CKEditor 3.0.2 till 3.1 - when you set 0 fir E.g. border style was removed from HTML.

This ticket looks like #4980.

NOTE: Firefox uses pt instead of px when you set image property to 0.