Small improvements after exc. 1 conclusions
Items filter moved to Index class.
Cart model bound to user and connected with CartPanel
Refactoring
Reading items from csv
Filtering : item spec instead of builder
Merge branch 'master' into dronka_ex1

Conflicts:
	src/pl/edu/agh/dronka/shop/controller/ItemsFilter.java
	src/pl/edu/agh/dronka/shop/controller/ShopController.java
	src/pl/edu/agh/dronka/shop/model/Index.java
	src/pl/edu/agh/dronka/shop/model/Item.java
	src/pl/edu/agh/dronka/shop/model/provider/ShopProvider.java
	src/pl/edu/agh/dronka/shop/view/CategoriesPanel.java
	src/pl/edu/agh/dronka/shop/view/PropertiesPanel.java