First steps towards better highlighting.

I've just implemented the base functionality for now. We'll need two
additional changes:

- Serve the html page as a resource when requested
- add `highlight-project` to the pipeline when importing or updating a
  project.

I'll be pushing more commits to this branch (or you can, @sbauer322) to implement these two other features.
Yeah, I can add a note to the README, but I should also make a check so that we can fail gracefully here if Pygments is not accessible.