Remove PID file once lwp was stopped

[Napsty]

After /etc/init.d/lwp stop was launched, the PID file still exists in /var/run/ (symlinked to /run in Ubuntu 12.04.2 LTS):

# /etc/init.d/lwp stop
Stopping server...Stopped process in pidfile '/var/run/lwp.pid' (pid 64261).
done.

# ll /var/run/ | grep lwp
-rw-r--r--  1 root       root          6 Aug 14 16:12 lwp.pid

pid file should be removed once service was stopped successfully.

[alexandrujuncu]

This actually needs to be moved as an issue on the other repo (https://github.com/lxc-webpanel/lxc-webpanel.github.com/issues) because the script that does that is there.