Custom 404 page.

Must stay in root of git repo for git pages to support it.
Refacotring: move everything from site to top level

and move images and js into subdirs.

This plays better with GitHub web hosting.
Improved custom 404 page

refactored some common styles into a new stylesheet "common.css"
Fixed: [regression] embedded fonts dont work
Fixed: text alignment is wrong on iPhone on 404 page
Updating gitignore and intellij files