i'm using this plugin for files and images uploads.
it has a very useful feature that generate thumbnails of every
uploaded image, based on the geometry given in the model definition.
now i want to change the size of one of the thumbnail: how can i re-
generate them for the already saved image?
i found this http://github.com/kete/kete/blob/master/lib/tasks/tools.rake
but i don't understand how to use it.