Add 'node' attribute to baremetal Allocation
Add 'node' attribute to baremetal Allocation

This attribute is only used for create_allocation. When it is
specified, an allocation is created for an existing active node
without going through the normal allocation steps.

Change-Id: Ia0e54d7a38bdc50b163113c6435d49b33ced947d

dtroyer/python-openstacksdk,stackforge/python-openstacksdk,openstack/python-openstacksdk,dtroyer/python-openstacksdk,openstack/python-openstacksdk,stackforge/python-openstacksdk