UUID support

Hi,

Please, review implementation of partition UUID support in wic.

It contains two options: --part-type and --use-uuid --part-type allows to set partition type UUID. It was incorrectly implemted in wic and now it's hopefully fixed.

--use-uuid makes wic to generate random globally unique identifier (GUID) for the partition and configure bootloader to boot from it using root=PARTUUID=<GUID> in kernel command line.

This technique makes boot process more deterministic and reliable for at least two reasons:
- It allows to boot the same image from different devices
- It fixes possible boot issues caused by using device names in kernel commandline as GUID doesn't change unlike device names.

Ed Bartosh (9):
wic: Add --use-uuid partition option
wic: Generate random uuid for partition
wic: Fix format string
wic: Refactored getting root device name
wic: Add parameter 'uuid' to Image.add_partition method
wic: Set type GUID and UUID for partition
wic: Use partition UUID in directdisk-gpt
wic: oe-selftest: Configure testing of gpt/UUID image
wic: Add help for --part-type and --use-uuid options

 meta/lib/oeqa/selftest/wic.py                      |  4 +--
 scripts/lib/image/canned-wks/directdisk-gpt.wks    |  2 +-
 scripts/lib/image/help.py                          |  9 +++++++
 scripts/lib/wic/imager/direct.py                   | 31 ++++++++++------------
 .../lib/wic/kickstart/custom_commands/partition.py | 21 ++++++++++++++-
 scripts/lib/wic/plugins/source/bootimg-efi.py      |  6 ++---
 scripts/lib/wic/plugins/source/bootimg-pcbios.py   |  3 +--
 .../lib/wic/plugins/source/rootfs_pcbios_ext.py    |  3 +--
 scripts/lib/wic/utils/partitionedfs.py             | 20 ++++++++++++--
 9 files changed, 68 insertions(+), 31 deletions(-)

--
Ed