created Cart and Order models and controllers, created associations between Cart, User and Product models as needed
implemented add to/remove from cart features; dropped product_qty method for now, next attempt will be taken upon in future
added tests for models and integration flow so far; re-factored views a little; added clear_cart method to Cart model and added ability to clear cart in the view/controller flow
Merge pull request #3 from WebDevFromScratch/alt_shopping_cart

Alt shopping cart