added nested restful routes for category product
added code to fetch products of specific category asynchronously
added cart controller and modified routes.rb to add a method, add to cart
1. added framework to build cart and add to cart functionality, 2. added database store for sessions, instead of cookie store for size concerns
added demo code to display cart
edited cart controller and updated acts_as_a_shopping_cart gem
fixed some session handling errors, and renamed cart_controller to carts_controller
fixed view when reloading, now the view remains the same
Merge pull request #2 from ketan21/filling_in_layout

Merged filling in layout branch into master.