Manage old images on update

[davidyell]

When new images are uploaded the old ones need to be managed so that the server won't just fill up with useless images.

[isemantics]

Maybe add a config setting to Proffer like cleanup with options:

• false [default]: Same behavior as now, images/files stay on server even though they may not be used/referenced anymore
• true: On update & on changed file, would remove the old files after successfully uploading/saving the new files.

(also needs to check if the file still actually exists)

[davidyell]

There is the cleanup shell which can clean out old images. I'd also like to try and avoid extra configuration, however I think that there is some thinking which needs to happen around updates and deletes, because currently a delete will remove images, when some people might not want that.