Deterministically identifying devices for testing

There seems to be an ongoing problem especially in the installation system for laptops, where the card reader and hard drive, both detected as 'sdX', are seen in a different order depending on the flavor of the installation (desktop, alternate, etc.). The certification website currently only allows one target device to be specified, e.g. /dev/sda.

Other related tests, such as the storage test may benefit from an updated way of detecting devices that are worth testing (for example, not testing and not failing on /dev/sdb being an empty card reader with no partitions).