Update 404.html

Added "sitemap: false" so whenever github pages updates to
jekyll-sitemap v0.4.0 it will automatically work.
Add logos

Coursera and Code School
Update Personal Data

Added Code School report card link and LinkedIn url.
Update About.html

Rewording
Create coursera.html
Update default layout

Added LinkedIn icon, links to coursera and codeschool.  Also reorganized
icons.