Updated to v1.8

- Added min-width to 'body' and 'html'
- Added CDN fallbacks
- Added IE Conditional to 'X-UA-Compatible' meta data
- Added litebox init to 'backbone.js' (moved from 'index.html')
- Added mixins: 'position-zero', 'vertically-align',
'gradient-linear-alpha' and 'gradient-radial-alpha'
- Added 'darker', 'dark', 'light' and 'lighter' classes to 'p' and
'h1-h6' elements
- Added 'no-color' class with 'darker-lighter' classes to 'a' and
'h1-h6' elements
- Added 'ap-*', 'op-*' and 'aop-*' classes to inline 'li' elements
- Added 'f-small', 'f-medium' and 'f-large' classes for font size
adjustments on form inputs/buttons
- Added 'vertical-center' and 'pos-zero' classes to #quickers section
- Added 'desktop-tablet', 'tablet-mobile' and 'mobile' classes/media
queries to be used with 'float-*' for float removal
- Removed mixin: 'gradient-overlay'
- Updated mixins: 'gradient-linear' and 'gradient-radial'
- Updated all CDN files to latest versions
- Updated demo