Add support for the Readability article text extractor, it runs on the SingleFile, Wget, and DOM dump output by default, but if none of those are available it will download the article from scratch to do text extraction. This release also officially adds Docker support for ARM architectures, including the Raspberry Pi. The image size was also shrunk from 1.5GB to 452MB by making sure unnecessary build tools are uninstalled after the package build process.