Typically if someone installed the agent as part of neutron::server
it would satisfy the dependency of installing python-neutron-lbaas
but if someone chooses to not install the agent as part of the
neutron::server class but still wants to use lbaas then they
will need to have the python-neutron-lbaas package installed.
Change-Id: I936e2177d00b57036f63b283af52f3009078d6bc