Fix LB, FW, and VPN references for Neutron post-upgrade in Kilo+

These services have moved to their respective repos and Neutron
config files for Kilo need to reflect that, once Juno gets
upgraded to Kilo. A link to the release note for this is provided
here:

https://wiki.openstack.org/wiki/ReleaseNotes/Kilo#Upgrade_Notes_6

Change-Id: If057c736996f7723f934fc47300dc81c899eb313