[vhost::proxy] Fix template configuration (proxyfy)

=> Set proxy_redirect to his default value (default).
The default replacement specified by the default parameter uses the
parameters of the location and proxy_pass directives. (The default
parameter is not permitted if proxy_pass is specified using variables)
This not our case =)

http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_redirect

And add a Host header to proxyfy