loadbalancer: Allow user to bind multiple public/private ips

Currently, a deployer can only bind on the loadbalancer 1 ip per
network (be it public, internal, admin, etc...).
If a deployer wants to bind to the ipv6 and ipv4 at the same time he
couldn't. This patch aims to fix that.
Merge pull request #552 from enovance/bind_ipv4_ipv6_haproxy

loadbalancer: Allow user to bind multiple public/private ips