Cleaned up comments and unnecessary constructors.
Removed constant values from TipCalculator and remade them as properties in FoodServiceTipCalculator and BaggageServiceTipCalculator.
Made HRService accept multiple Employee classes and set up PaymentType enum to allow for different calculations based on how often an employee is paid.
Minor change to number formatting in the Startup class.
Added a throw exception in case there are multiple employees with the same employee number.