Neutron should not use the neutronclient utils module for import_class
Neutron should not use the neutronclient utils module for import_class

Fixes code to use openstack.common.importutils instead.

Change-Id: Ia449f8b1d7d03f37483cfdc595ad77e71ea6598c
Closes-bug: 1366917

gkotton/vmware-nsx,gkotton/vmware-nsx