Disk utilisation plugin.

Returns metrics for all devices listed by iostat that do not start with
'dm-'. The metric is the %util over a period of 5 seconds from when the
check is run.

Required by the CDM checks/alarms patch in ansible-lxc-rpc
I have no specific reason for doing the split separately, I probably just did it like that as I was working out how to break the data up.

I strip whitespace from the beginning and end of the data before I split it into lines. The only reason not d == True, that I can see, would be if there were blank lines between the lines of data. If that happens then the iostat binary has changed. Really this script should just have better data validation.