Use new enginefacade for address_scope_db
Use new enginefacade for address_scope_db

Usage reader and writer for db operations with address_scope.

Partially-Implements blueprint: enginefacade-switch

Change-Id: I7152fad397552975fcb726e760a8070e15b05c2c

noironetworks/neutron,eayunstack/neutron,mahak/neutron,cloudbase/neutron,cloudbase/neutron,openstack/neutron,mahak/neutron,noironetworks/neutron,huntxu/neutron,mahak/neutron,eayunstack/neutron,openstack/neutron,openstack/neutron,huntxu/neutron