CLOUDSTACK-7121: agent: Make IPv4/IPv6 preference configurable
CLOUDSTACK-7121: agent: Make IPv4/IPv6 preference configurable

This allows us to have the Agent connect to the Management Server
over IPv6 if that is listening on :::8250

With this patch it is possible to deploy a IPv6-only KVM Agent where
IPv4 traffic is still forwarded over the bridges, but the KVM Agent
itself does not have IPv4 connectivity.

jcshen007/cloudstack,DaanHoogland/cloudstack,GabrielBrascher/cloudstack,resmo/cloudstack,jcshen007/cloudstack,GabrielBrascher/cloudstack,DaanHoogland/cloudstack,wido/cloudstack,wido/cloudstack,resmo/cloudstack,resmo/cloudstack,wido/cloudstack,GabrielBrascher/cloudstack,DaanHoogland/cloudstack,wido/cloudstack,DaanHoogland/cloudstack,jcshen007/cloudstack,jcshen007/cloudstack,jcshen007/cloudstack,wido/cloudstack,wido/cloudstack,resmo/cloudstack,jcshen007/cloudstack,jcshen007/cloudstack,GabrielBrascher/cloudstack,DaanHoogland/cloudstack,resmo/cloudstack,GabrielBrascher/cloudstack,resmo/cloudstack,DaanHoogland/cloudstack,DaanHoogland/cloudstack,wido/cloudstack,resmo/cloudstack,GabrielBrascher/cloudstack,GabrielBrascher/cloudstack