Even more bugfixes and touchups

[djmetzle]

Well poking around at the new Dockerific deployment of charge, we found some interesting points and even a few bugs.

• Fix the hard fail on empty upload bug
• Add more S3 metadata to the views
• Fix the missing pngquant dependency (how did that ever work?)

Thanks @danielbeardsley !

[djmetzle]

Cool. No comments. :+1: