Merge IE7 and IE8 SCSS for Base

Updated refrences in dependant files
Merge IE7 and IE8 SCSS for Grids

Updated refrences for imports
Merge IE7 and IE8 SCSS for CLF theme

Updated import statements
Merge IE7 and IE8 SCSS for GCWU theme

Updated dependant imports in Intranet theme
Merge IE7 and IE8 SCSS for Intranet theme

Update import statements and used a placeholder to reduce duplication
No units for zero values
Merge pull request #1023 from nschonni/remove-zero-units

No units for zero values
Merge pull request #1020 from nschonni/merge-ie-scss

Merge IE7 and IE8 SCSS
Resolved merge conflicts. Extended IE7/IE8 SCSS consolidation to other themes.
Merge branch 'master' into experimental