Add product short description to modal

I've added product short description to "add to basket" modal and also updated product generation skeleton template to remove `basket_product` product block override.

Preview:

![capture decran 2014-01-24 a 14 49 03](https://f.cloud.github.com/assets/103900/1995209/1f0fbd40-8500-11e3-8bfa-9019c19efe37.png)