Add open source fonts from The League of Movable Type to design assets

I selected sans serif and script fonts published as open source by:

The League of Movable Type
https://www.theleagueofmoveabletype.com/
Add bootstrap 2 (v2.3.2) and bootstrap3 (v3.0.0) to design assets
Move design themes to a subfolder in design

The intent is to group the themes and make room for orthogonal
experiments with type and colors.