Feature: Shopping cart in Mobile ordering app

[evereq]

We need to implement a "shopping cart" feature in the mobile customer ordering app.
It should be possible to enable/disable the shopping cart in the mobile app. If shopping cart disabled, it should work like now - single button click, purchase the product. If shopping cart enabled, click on "Buy" should add the product to Shopping Cart, but the customer can continue browsing more products, add them to the shopping cart, and next checkout all of them together as a single order.

Note: I think on the backend and in Merchant / Carrier apps we already support multiple products in a single order. It's only we need to implement that feature in the customer mobile app.