Blank <vip/> tags appear in config.xml
After adding a CARP VIP (at least, possibly others), you end up with a <vip/> or <vip></vip> tag above the configured VIP. To replicate, just add two CARP IPs and check the config.xml.
It makes blank entries show up in the VIP lists.
Do not try to bring down a CARP VIP for an entry that does not exist yet. Fixes #819