fix: Don't fallback to root path, if path is omitted.

[dsturm]

When creating an auth user in ploi.io, we can ommit the path. In CLI, the path argument is also stated as optional but falls back to / root. Therefor creating a user will result in a location rule in auth.conf for /.

location / {
auth_basic              "Authentication Required";
auth_basic_user_file    "/home/ploi/site.com/.htpasswd";
}

whereas an omitted path in ploi.io will not add a path specific rule

auth_basic              "Authentication Required";
auth_basic_user_file    "/home/ploi/site.com/.htpasswd";

Having location / {} in auth.conf throws an error in Nginx:

nginx: [emerg] duplicate location "/" in /etc/nginx/sites-enabled/site.com:30