Output data in a format as required by check_mk

The data is expected in a format like:

  status | item_name | performance_data | check output

as specified on http://mathias-kettner.de/checkmk_localchecks.html
Note: we don't have performance data, that's why we use "-" to skip
the third column.

Using this script with check_mk is as simple as placing the file
inside /usr/lib/check_mk_agent/local/