Add "jailflag" to nodes table. In the parent (phys) node, it means the
node supports and is doing jails. In the virtual node, it means it is a jailed node. It should be obvious that these are set the same for a node; it means I do not have to query two nodes to find out what to do. When set, the parent gets a different set of accounts and mounts, and we hand out accounts to the jailed node.