Track apinger status in /var/run instead of /tmp

This is a one line status file updated every few seconds. It would be
better to store this in /var/run since that is (always?) a ram disk on
pfSense. Especially important on systems with flash storage.

see: http://forum.pfsense.org/index.php/topic,52734.msg281834.html#msg281834
Merge pull request #487 from rdlugosz/change_apinger_status_path

Track apinger status in /var/run instead of /tmp