Upgrade spinner

use vertical color for its color
create global class for vertical
refactor SB code to use this class
I know what's going on here but it could be useful to copy explanation from [_smart-banner.scss](https://github.com/Wikia/mercury/pull/481/files#diff-5c3d3a345c316d6e8759be605554da0eL130) or reference to it.