This patch adds codes to support the fault field exposed from ironic API.
Querying nodes with specified fault is also supported as well.
Story: #1596107
Task: #10469
Partial-Bug: #1596107
Depends-On: https://review.openstack.org/556015/
Change-Id: I429df0ab5ea39140a2b988d5dfdacb24a67b955e