Add sass-globbing dependency?

[jakubpawlowicz]

This is likely dough's responsibility to define it.
See:

• https://github.com/moneyadviceservice/car-cost-tool/commit/b0ce65baeec12ae66e7cdc2653effabfbee3046f
• https://github.com/moneyadviceservice/dough/blob/master/stylesheets/_lib.scss#L8