layerman: drop meta-n450, it doesn't exist anymore

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
layerman: switch meta-dominion to daisy branch

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
local.conf: disable ISO image by default

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
local.conf: work around grub build failure

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>