Added interfaces for Elevator Control System
Added initial imlementations for Elevator Control System
Added enum for elevator status
Added status check to Elevator class
Removed pickup since we can just check to see if the elevator is not occupied then add destination
Added case structure to being step logic
Added Elevator direction
Added step logic based on elevators direction
Added pickup and destinatoin.  Pickup is when a user is outside and destination is when a user is inside
Added test cases for Elevator
Documented design of the project
Added exception for invalid elevator numbers
Added ElevatorControlSystem initialization method for elevators
Added test cases for multiple floors