Update gems
Add PostCSS Twitter and Gitter
Update Rake
Fix section 1 slides
Update Usage section
Add PostCSS benchmark
Update plugins examples
Fix own plugin example
Use same rules in CSS examples
Fix compare slide
Clean up slides
Normalize Less name
Use benchmark on full GitHub CSS
Fix fonts on Safari
Add Evil Icons ad and fix typo
Markup fixes
Add WSD to README.md
Fix JS syntax
Translate to English