Feature request -- Image replacement

rutt

I'd like to be able to have an image id that behaves like a unix soft link or a web redirect. Here is a sketch for api calls that would support this:

CreateRedirect(original_image_id) -- Create the new link originally to original_image_id. Return the image id of the created link.

Redirect(redirect_image_id,new_image_id) -- Point the link at a different image.