Minify web assets.

This branch minifies all CSS and JS for the web asset. We were able to get away
with nonmified assets earlier on simply because the site didn't use too much
CSS or JS at the time.

Flask-Webassets strips all css/js of comments and whitespace.

@jhladky, here's some broken stuff I'm unsure of how to fix:
- [ ] tutoring page

I also intend to minify html soon using a django plugin that has become
generic.