content/files: Move files under Pelican
pelicanconf.py: Tell Pelican about content/static/files

Needs my Pelican patches to copy directories [1], and it's probably a
good idea to use my mkdir_p patch too [2].

[1]: https://github.com/getpelican/pelican/pull/665
[2]: https://github.com/getpelican/pelican/pull/664