New design

**Overview**

* removes unnecessary images and SVG files
* introduces new, more readable styling
* cleans up Jade/HTML
* adds throwing errors on compile, thanks to #3
* updates `.gitignore`
* updates README.md with `human-model` and `human-view` deps

**Before merging into** `gh-pages`
* Fix the `slider` positioning in the navigation
* Add `active` class to the link corresponding to slider position
* Clean up headings in `human-view` and `human-model` for proper structure and hierarchy in the navigation

:gift_heart: