Moved business logic to new module (Controller).
Created a new UI module for handling user input.
Created a new entry point (rates.rb) to run the program.
Removed obsolete files. The code from them is now moved to controller.rb.
Added logging of the number of successfully stored exchange rate records.
Changed UI command type from integer to string for robustness.
Renamed storing.db to db.rb
Renamed module Storing to DB.
Started work on fetching statistics. Does not compile!