Remove openstack.common.exception usage
Remove openstack.common.exception usage

This file is deprecated, stop using it.

Change-Id: I5d79b8c0134bb5f4021487542d4d0a964281b8bf
Fixes-Bug: #1208734

dougwig/x-neutron-lbaas,gandelman-a/neutron-lbaas,gandelman-a/neutron-lbaas,gotostack/neutron-lbaas,gandelman-a/neutron-lbaas,citrix-openstack-build/neutron-lbaas,gotostack/neutron-lbaas,gotostack/neutron-lbaas