The private IPs are more useful for having nodes to
communicate with each other in multi-node jobs.
This change extends the /etc/nodepool with two new files.
* primary_node_private The private ip of the primary node
* sub_nodes_private The private ip of the sub nodes,
in the same order as the floating ones.
This change helps in simplify the devstack-gate multi-node change.
This change causes DB schema change, both node and subnode table
extended with an ip_private field.
Change-Id: Ib7b29afbfae877e6edeea6568732c54c3d9e12f1
9cac605d8f