ikev1: Send INITIAL_CONTACT notify in Main Mode

We currently send the notify in Main Mode only, as it is explicitly not allowed
by RFC 2407 to send (unprotected) notifications in Aggressive Mode. To make
that work, we'd need to handle that notify in Aggressive Mode, which could
allow a MitM to inject such notifies and do some harm.

Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>
ikev1: Don't inherit children if INITITAL_CONTACT was seen

Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>