Read PublicCode.yml

[giosce]

PublicCode.yml hopefully should get broad usage to describe civic tech open source projects.
Thus, the crawler should consider picking up project info from that file if it exist in the repository.

[themightychris]

This will require finishing #62 or some other branch that just uses it as inspiration to give us the basic ability to load content from the referenced git/GitHub repository for each project and capture that data as part of the snapshot.

From there, publiccode.yml is just one of many potential files we might want to capture in the snapshot (others include civic.json, README.md, and GitHub's community health files)