ViaggioEdiView Refactoring

Added ViaggioValidationService
Refactored ViaggioService.Save so that validation is moved outside this
service.
Refactored ViaggioEditPresenter so that it checks for validation on save
and take care of exceptions.
Refactored ViaggioEditView so that on error the user cannot close the
form.

These refactorings are yet to be tested