[ADMIN_API] Don't change LB state on node state change

It is possible for a monitor problem to happen at the same time as a DELETE
changing state from PENDING_DELETE/DELETED to DEGRADED/ACTIVE.

This patch stops the state changing if the initial state is not correct

Change-Id: I4af872c3eb05a526acc489029c29e037596b9abe
[API] Only allow int vips on create

Change-Id: I89dd793568e015bafd37ed98ba4db2426e5ae344