Fix for regression in 4.x caused by usage of javax.imageio.ImageIO

Added [com.twelvemonkeys.imageio](https://github.com/haraldk/TwelveMonkeys) to maven dependencies to [broaden JPEG support](https://github.com/haraldk/TwelveMonkeys#jpeg) when using ImageIO. It is automatically registered by the ImageIO registry and service lookup mechanisms. Fixes IDPF/epubcheck#464.