node-list to show the maintenance field

The review https://review.openstack.org/#/c/84685/ added the maintenance
field from nodes to be shown in the GET /nodes. This patchs makes the
necessary changes to the CLI to reflect the changes in Ironic.

Change-Id: Iffb639f1e995ef73a5bda6dd3961a13ba5d865d0
Merge "node-list to show the maintenance field"