Add fixes for faulty Sass @import paths and negative values.
Change Sass headings file name and import path.
Merge pull request #596 from MickeyKay/sass-header-file

Change Sass headings file name and import path.
Merge pull request #594 from MickeyKay/sass-fixes

Add fixes for faulty Sass import paths and negative values.
Closes #588.
Merge pull request #1 from Automattic/master

Sass Updates
Merge branch 'master' into Sass-Less-Port
Fixed layout file references, Updated headings.less filename