Assignment 2 clarification and test case added

Hi students,

Since the exchange operation is confused. I will clarify it as follow: 

- The default currency should be: NOK

- The command exchange only valid if from currency is equal to account currency (Test list will only have valid command)

- After exchanging, the balance and currency should be changed accordingly.

- I provide you an input.txt and output.txt for you to test. (Remembering that each command in input.txt will be sent to the group by all the clients, so it will be n times executed)

Regards,

Dat