Refactored AddCommand to use simpler constructor. Added CommandExecutionException. Separated Tests into a separate folder.
Refactor time to date
Refactored EditCommand to use simpler constructor
Added setTaskNumber in EditCommand
Refactored EditCommandTest to use simpler constructor
Added CommandExecutionException to DeleteCommand.execute()
Refactored DisplayCommand
Applied singleton pattern to UserInterface. Edited CloseCommand
Modified AddCommand to default to RepeatFrequency.NONE
Merge pull request #45 from andhieka/working

Refactored AddCommand to use simpler constructor. Added CommandExecution...