vrrp sync group: Send prio 0 when entering FAULT state

This fix will send prio 0 (VRRP_PRIO_STOP) when the VRRP router transists from
MASTER to FAULT state. This will make a sync group leave the MASTER state more
quickly by notifying the backup router(s) instead of having them to wait for
time out.

Signed-off-by: Jonas Johansson <jonasj76@gmail.com>
vrrp sync group: Quick sync group transition

In a sync group, when waiting for all instances to want master state, this
fix will check the instances for transition every advert interval instead of
every third. This will make a sync group transition occur more quickly.

Signed-off-by: Jonas Johansson <jonasj76@gmail.com>
Merge pull request #34 from jonasj76/quick-sync

Faster sync group transition