Make pandoc-rendered PDF more attractive

[garrettr]

Pandoc can render encryption_works.md to a number of formats. We currently offer html, pdf, and odt copies of the paper on the FPF site. I just tested the PDF rendering and it looks pretty good, but there are some issues that need to be fixed:

• Some image formatting is messed up
• Table of contents
• Footnotes (links work fine though)
• Page numbers

[garrettr]

I still like using Pandoc, but if we switch to using GitBook in #89 we should probably just use their PDF export capability instead.