Support for drbd stacked resources

[cvinh]

I understand that stacked drbd resources cannot be managed in LCMC because the third node may not be in the cluster... By the way, as soon as we touch drbd configuration with LCMC, the stacked configuration parts in /etc/drbd.d/res.conf are deleted... Could it be possible that the drbd stacked configuration is not deleted ? We should copy manually the conf on the third node to make 3-node drbd work, no other choice if the third node is not in the cluster... Best regards and congrats for the wor