MVC Clean Up

[Chrstjan]

Some model code is inside some controller code this should be moved into it's own functions

• retrieveLocalStorage functions contains controller & model
  The local storage should be moved into a function called getLocalStorage
  The retrieveLocalStorage function should be renamed to retrieveShoppingCart

• removeFromCart function should call the getLocalStorage function instead of having model code

• cartCallback function should call the getLocalStorage function instead of having model code
  The model code in the if statement should also be moved into a model function called setLocalStorage