elementary CSS 2.3.0

*First major update in 394 days!*

**Project Changes**
- Isolated framework files from documentation files
    - Only files in the `framework` folder are to be used in production
- Removed wiki pages in favor of inline documentation
- Removed SCSS and Bourbon in favor of vanilla CSS
- Removed YUI Compressor
- Included license file with icons
- Switched from MIT license to public domain license
- Improve Opera and Safari support
- Improve `.gitignore` file
- Simplify `README`
- Improved code formatting

**Aesthetic Changes**
- Added custom selection color to match elementary's own website
    - Selecting text now disabled `text-shadow` to improve readability
- Switched global font from Droid Sans to Open Sans to match elementary's website
- Switched monospace font to Inconsolatas to improve readability
- Updated heading font sizes to match elementary's website
- Added `.h1` through `.h6` classes for applying heading styles to inline elements
- Improved `blockquote` styles to improve readability
- Updated `a` styles to match elementary's website
- Improved `del`, `ins`, `code`, and `kbd` styles for readability
- Updated button styles to better match GTK theme
- Added light button
- Added `.active` class for buttons
- Improved custom form elements with jQuery
- Updated form graphics to better match GTK theme
- Form graphics are now in SVG format
    - Separate HiDPI graphics were removed
    - Fallback PNG exists
- Removed toggle switches
- Updated text field styles to better match GTK theme
- Updated slider graphics to better match GTK theme
    - Fixed cursor on slider
- Updated progress bar graphics to better match GTK theme
- Updated infobar graphics to better match GTK theme
- Updated navigation bar to better match elementary's website
- Optimized icon CSS
- Icons are now listed alphabetically in the documentation