Improve Windows ping regexp
Improve Windows ping regexp

Windows reports "Reply from <interface>: Destination host unreachable."
for a host which is down, but the regexp checking for success only looks
for "Reply from", so thinks the ping succeeded.

Fixes #72

jamesoff/simplemonitor,jamesoff/simplemonitor,jamesoff/simplemonitor,jamesoff/simplemonitor,jamesoff/simplemonitor