git-p4: introduce skipSubmitEdit

git-p4: introduce skipSubmitEdit

Add a configuration variable to skip invoking the editor in the
submit path.

The existing variable skipSubmitEditCheck continues to make sure
that the submit template was indeed modified by the editor; but,
it is not considered if skipSubmitEdit is true.

Reported-by: Loren A. Linden Levy <lindenle@gmail.com>
Acked-by: Luke Diamand <luke@diamand.org>
Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>