polish_up_new_file_and_image_uploading suggested there are issues with transparency and more generally with gifs in ImageScience.
Might be worth another look after we get the new attachments system running.
actually, this is now how it works (dependency is fully tracked in Gemfile).
Consider defaulting to rmagick instead of ImageScience+discussed in support tickets
Consider defaulting to rmagick instead of ImageScience+relevant user stories