Adding changes to OpenStack CPI for volume type.

Conflicts:
	bosh_openstack_cpi/lib/cloud/openstack/cloud.rb
	bosh_openstack_cpi/spec/integration/lifecycle_spec.rb
	bosh_openstack_cpi/spec/unit/create_vm_spec.rb
Openstack boot_volume_type -> boot_volume_cloud_properties

Signed-off-by: Edward Zhang <zhuadl@cn.ibm.com>