Serve devserver home directories from /var/home-wwwroot

Summary:
Users can host static files under server domain ~username directory,
for example https://windriver.nasqueron.org/~dereckson/

There is no CGI support, as we use nginx, not Apache or lighttpd.

Directories are stored in a location outside the home directory.
That allows users concerned by privacy to protect the home directory
with chmod 700 while the public_html directory can still be read.

The default nginx configuration takes care of the whole domain,
home directories and other services.

The node.get_all_ips function lists the unique addresses currently
assigend to the network interfaces, both IPv4 and IPv6. This is leveraged
to build the list of the addresses matching the server for nginx.

Services for the devserver include Poudriere logs.

API CORS is for the Salt server config read by infra.nasqueron.org.

Test Plan: Tested on WindRiver

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D3454