respect 'access froxlor directly via hostname' and 'custom docroot in ip/port' setting in nginx, refs #920

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
respect ip/port-default-vhost-config-for-every-domain and system-defaultvhost-conf setting in nginx and lighttpd, fixes #916

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>