Always set the width and height attributes

Issue Summary

Whizzywig should always add the width and height attributes to IMG elements. The reason for this is that it makes pages easier to layout for the browser and also for things such as Lightbox and its relatives.

In the case of Lightbox, etc., if there is an image in the popup which has not been cached by the browser before, it doesn't know how large the dialog should be and often sizes it incorrectly.