Purge all nginx packages, just like we do on apache2

Only purging "nginx" will leave "nginx-full" (together with some others) still
installed. It's not reproducible on the config-changed hook, since it stops the
actual engine before starting apache2. But when the machine restarts for
example, apache will fail to start if ngix-full starts before it.
[hackedbellini] This is to fix using wordpress with apache2. Without this, apache will fail to start everytime the machine restarts.
Added listen.mode