Missing baremetal NodeState API test

As a part of blueprint, this patch implements following API test -
NodeState APIs -
1. Retrieve a state information of a node.

part of blueprint: missing-baremetal-api-test

Change-Id: I537caef5ecac0cef34039a6bb945309472a169a8
Merge "Missing baremetal NodeState API test"
Merge branch 'master' of https://github.com/openstack/tempest