Shrink images size with imageoptim
Add doctype, clean metas

- add doctype
- add lang
- clean meta charset
- false is not a correct value for user-scalable
- type is not necessary for link
Self-ending tags are not mandatory
center tag is deprecated, use css instead
tt tag is deprecated, use code tag instead
Improve menubar
Indentation is now 2 spaces in all files
Add polyfills for IE8-

HTML5 and mediaqueries polyfill