do not fail when ssl cert not present.

[Christ-Jan Wijtmans]

I tried to not fail the nginx server if ssl cert is not available.
However the directive is not even allowed inside a statement.

        if (-f /var/www/x/etc/ssl.crt)
        {
               ssl_certificate /var/www/x/etc/ssl.crt;
               ssl_certificate_key /var/www/x/etc/ssl.key;
        }


Also i do not believe its proper to fail the entire server if one
server block fails.