3917 Error if external author info present & import for others unchecked

https://code.google.com/p/otwarchive/issues/detail?id=3917

If you enter external author information and don't select 'Import for others ONLY with permission,' the work imports as yours. Let's give an error that says, 'You have entered an external author name or e-mail address but did not select "Import for others." Please select the "Import for others" option or remove the external author information to continue.'