Added delegate setting function to swappable rating cell to allow emitting value changing events.
Hooked delegate to the bill calculator view controller.
Added main tipster view to storyboard and use it with the bill calculator view controller.
Fixed isTaxInclude switch in storyboard and controller.
IsTaxInclude in Bill class is default to true.
Fixed BillCalculator view controller to load default data from Bill class on loaded.
Rating value in swipeable rating cell is changed to float.