Updated the location of the order_tabs override

The override broke with change at https://github.com/spree/spree/commit/22a70b62aa873ce23a584ad07e729f6e95a04baa#diff-2f549f834ee39b2abfde52d8901b984c

Also, changed the link_to method to an icon, which matches the other order tabs.
Set working version of sass-rails.