wifiChecker log message format is inconsistent #75

Update wifiChecker.sh with log messages matching basic date-first format.
simply use following as an example perhaps, setting INFO/WARNING/ERROR as appropriate?

echo "$(date +"%b %d %Y %T") ERROR BrewPi: wifiChecker: This script must be run as root: sudo ./wifiChecker.sh" 1>&2

instead of
echo "This script must be run as root: sudo ./wifiChecker.sh) ($(date))" 1>&2