This way the KPMcore libpartedbackend scanner won't filter out Parted
devices of type UNKNOWN.
CAL-349

Also remove outstanding SetPartFlagsJobs when deleting a new partition.

This reverts commit c64eef54f6584b26f14933f0c8e600d5ad2dacbb.

CAL-195

If FileSystemFactory::init() is not called early enough, we won't get
access to some information such as the number of used sectors.

Fixes #75

Fixes #12