MidoNet plugin needs the 'neutron_lbaas' module available when it
starts up without needing to start the LBaaS service. After the
advanced service split, however, devstack clones 'neutron_lbaas'
only when the 'lbaas' service is enabled. To get around this
conflict, clone 'neutron_lbaas' everytime midonet is configured
as the Neutron plugin.
Change-Id: Ide620db383fc44a66a84d00b2365ec2e846469fe
Closes-Bug: 1402242