Bump Sass to latest 3.4.x

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Move global Sass partials to open_project_global

Avoid potential naming collision with Foundation for Apps.

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Integrate Foundation global styles

Signed-off-by: Alex Coles <alex@alexbcoles.com>