Introduce provision states: AVAILABLE, ENROLL

BaremetalProvisionStates.NOSTATE (``None``) was replaced by AVAILABLE
("available") in Ironic version 1.2. ENROLL ("enroll") state was introduced
in version 1.12.  This patch also updates the
BaremetalScenarioTest.terminate_instance method to wait for etiher NOSTATE
or AVAILABLE.

Change-Id: I067504e49f68929298c91e61819aa9a61169fe52

ironic_tempest_plugin/tests/scenario/baremetal_manager.py

@@ -36,7 +36,9 @@ class BaremetalPowerStates(object):
 
 class BaremetalProvisionStates(object):
     """Possible provision states of an Ironic node."""
+    ENROLL = 'enroll'
     NOSTATE = None
+    AVAILABLE = 'available'
     INIT = 'initializing'
     ACTIVE = 'active'
     BUILDING = 'building'
@@ -175,6 +177,7 @@ class BaremetalScenarioTest(manager.ScenarioTest):
                               BaremetalPowerStates.POWER_OFF)
         self.wait_provisioning_state(
             self.node['uuid'],
-            BaremetalProvisionStates.NOSTATE,
+            [BaremetalProvisionStates.NOSTATE,
+             BaremetalProvisionStates.AVAILABLE],
             timeout=CONF.baremetal.unprovision_timeout,
             interval=30)