#409 Post-Python 3: submitclonepub doesn't validate pub_id correctly

[Ahasuerus]

edit/submitclonepub.py doesn't validate pub_id correctly. Id no pub_id is specified, it generates a Python/ Apache error. If a non-existing pub ID is specified -- either 0 or an integer number that doesn't correspond to an existing publication ID -- it creates a submission without validating the pub ID.

Note that proper validation logic should be added both to edit/submitclonepub.py AND to common/viewers.py because a publication record may be deleted between the time the submission was created and the time it was pulled up on the submission review page.