Add backbone.js 1.1.2

From http://backbonejs.org/backbone.js
Add underscore.js 1.6.0

From http://underscorejs.org/underscore.js
Add jquery.js 2.1.1

From http://code.jquery.com/jquery-2.1.1.js
Add placeholder.png

From https://raw.githubusercontent.com/addyosmani/backbone-fundamentals/gh-pages/img/placeholder.png
Add blank files
Move index.html to site
Fix file missing