This allows security groups to be created and attached to the neutron
port that the loadbalancer is using on the subnet.

The security group ID that is assigned to the nodes needs to be
provided, to allow for traffic from the loadbalancer to the nodePort
to be refelected in the rules.

This adds two config items to the LoadBalancer options -

ManageSecurityGroups (bool)
NodeSecurityGroupID  (string)