This commit brings back all headers previously defined in port443.conf.
The current setup has been missing them since the `add_header` directive
was added to the individual `location` blocks (for CSP). The nginx
manual states:
> These directives are inherited from the previous configuration level
> if and only if there are no add_header directives defined on the
> current level
http://nginx.org/en/docs/http/ngx_http_headers_module.html#add_header
None of the headers are important enough that they would have to be
added to all possible `location` blocks. Adding them to the root block
for each site will be sufficient.
Conrad Hoffmann