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.
Mention issues related to the TODOs in the TODOs.
Merge pull request #15 from jcsims/no-more-clygments

First steps towards better highlighting.