Fix import for LB
Fix import for LB

Due to the split between neutron core and advanced services,
LB is now in its own separate repo. This patch updates
the import statement to point to the new class.

Change-Id: Ic1a347eaa0bc777c2e86414da9adef92712bae97

yamt/networking-midonet,midonet/python-neutron-plugin-midonet,JoeMido/networking-midonet,JoeMido/networking-midonet,midonet/python-neutron-plugin-midonet,yamt/networking-midonet