Require newest blivet (python-blivet 1.4) (vtrefny)
    
    - Allow using of free space inside extended partitions for LVM (vtrefny)
    - Use sys.exit instead of blivetgui.quit in certain situations (vtrefny)
    - AddDialog: fix size selection for btrfs disks (vtrefny)
    - Remove obsolete option to embedd blivet-gui to another app (vtrefny)
    - Remove some obsolete/unused BlivetUtils methods (vtrefny)