nginx config does not handle IPv6 addresses

[Lee Trager]

nginx is not being configured properly for IPv6 addresses. It is missing the [] around the IPv6 address before the port. This is causing nginx to fail to start which is needed to start the ephemeral environment.

I only have 1 region controller in this setup but it has access to both IPv4 and IPv6. nginix should not consider this two different servers.

Currently:
upstream maas-regions {
    server 10.0.0.2:5240;
    server fc00::216:3eff:fee4:2cd0:5240;
}

What it should be
upstream maas-regions {
    server 10.0.0.2:5240;
    server [fc00::216:3eff:fee4:2cd0]:5240;
}