Add driver internal info field to nodes table
Add driver internal info field to nodes table

Driver should have its own infos, which are not input from admin like
driver_info and they may vary during the deployment process.
They can only be used by driver itself.

Implements blueprint driver-internal-info
Change-Id: I4fc647708d899047f5a802b1d7301d403c9f580f

naterh/ironic-specs,bcornec/ironic-specs,openstack/ironic-specs,NaohiroTamura/ironic-specs