Strip old project artifacts from static source

Removes old project-specific stuff from the base static sources. It causes all sorts of problems if you try to update old projects.

Makes a few opinionated decisions

- Open Sans for the sans-serif
- Lora for the serif
- Source Code Pro for monospaced type

I also uncommented all the stuff from `composer_theme.sass`. It seemed pretty arbitrary which ones were commented out. I think this always kept me from fully embracing it.