Disable "add to cart" when variations is out of stock.

Hi robert,

In the upcoming release of WPeC 3.8.11, we have custom JS events you can hook into. We’ll have one for the variations select fields to ensure that you can hook in when fields are selected and run any javascript you like when that occurs.

See https://github.com/wp-e-commerce/WP-e-Commerce/commit/d52af36c33a84f730929b904c1baf797b652c0b4

Fantastic!!! Thank you!!!