Cleaning up slider SCSS
- Make sure as much as possible is behind optional classes
- Rename everything to follow style convention
- Add new class for JS binding
- Rearrange file to take advantage of SCSS nesting with &
Merge pull request #565 from sgomes/material-sprint-slider-css-pass

Cleaning up slider SCSS
Updating radio SCSS to follow best practices
Fixing up ripple CSS classes across the board.
Renaming wsk-ripple--recentering to wsk-ripple--center