WPSC Theme CSS cleaning.

Minor clean-up to the theme css files.
- Extra whitespaces and old commented out code removed.
- Typo corrected: .default_ * to: .single_product_display .wpsc_variation_forms and .single_product_display .wpsc_quantity_update (are these needed or redundant?).

Signed-off-by: Andrew <macbook-131@macbook-131s-MacBook-Pro.local>