Provide HDD test feature on live CD

Alongside the memtest option it would be great to be able to do a pre-flight test of the health of the hard disk, possibly including SMART statistics and a full read test and performance test of the drive(s). Helpful for a new install, or diagnosing problems with an existing install. Sometimes people come to Ubuntu following a bad experience with unreliability on other operating systems, if the underlying issue is a bad drive then it would be good to identify this in advance so that Ubuntu does not get mistaken for the cause of problems experienced - which will probably be perceived as worse than the previous OS if the drive is deteriorating.