Log Message:
textproc/paperoni: update to 0.5.0

This release adds the following:
-Table of Contents generation of article headers upto h4
-An --output-dir flag for specifying the download directory for non merged
articles in #15
-Add output_dir to cli argument #15
-CSS styling of the epub document for better presentation. This also allows
users to convert to PDF using tools and have a decent typesetting
-Generating a list of the articles that were partially downloaded
-This release also includes a fix from #17