Fix theming in Gold Cart

[JustinSainton]

From Bitbucket:

Thank you for all your help. I appreciate everything you did. I would BEG you to have the programmers figure out why in list view everything follows my theme and in Grid view I get colors that have NOTHING to do with my theme. I also BEG you to have them fix the Variant text that ONLY shows up on Grid view. I won't be able to use the plug in again until that is fixed. I know the shopping cart is free, but I pay for Gold Cart every time and I can't afford to also pay for support, to change colors on the GOLD CART CSS and to change that text from no where. This is a huge issue. If they would allow us to move the gold cart css to our theme folder so we didn't have to use FTP, like they do for the actual shopping cart that would alleviate the color issue.
"use theming API for file registration"

The crux of the issue here is ensuring that Gold Cart CSS is registered properly so that it can be moved to the active theme folder.