use attribute functions/operations from neutron-lib
use attribute functions/operations from neutron-lib

neutron-lib now contains the functionality from neutron's attributes
module. This patch moves the local references over to neturon-lib's
implementation.

Change-Id: I25de1414a59a6b7dea4fe2b7bc5d536189b05071

openstack/networking-sfc,openstack/networking-sfc