Before when a node was failing, all the nodes would bump the lamport time of all their
entries. This means that if a node flap, there will be a storm of update of all the entries.
This commit on the base of the previous logic guarantees that only the node that joins back
will readvertise its own entries, the other nodes won't need to advertise again.
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>