Use "noconfig=sudo" to work around live-config bug

See http://bugs.debian.org/701788 for details. But this bug means
that subsequent live-config scripts were not executed and due
to this auto-login was not enabled and sshd host keys were
not generated, etc.

Also use the shorter syntax for the username.

auto/config

@@ -70,6 +70,6 @@ lb config noauto \
 	--iso-publisher "Kali" \
 	--iso-volume "Kali Live" \
 	--linux-packages linux-image \
-	--bootappend-live "boot=live config live-config.username=root hostname=kali" \
+	--bootappend-live "boot=live noconfig=sudo username=root hostname=kali" \
 	$lb_opts \
 	"$@"