- fixed use of uninitialized values in KIWIBoot.pm while
  in kiwi's format conversion mode
- fixed setup of build type in KIWIXML constructor. While testing
  I found that e.g the format conversion failed because there
  was no machine section found. But for the selected type and profile
  there was a machine section specified. The KIWIXML::setBuildType
  function was never called thus the default type applies which was
  of type iso and there no machine section existed.
- fixed update of machine section in case of a xen dom0 setup
  the vmdisk entry is mandatory now thus the section has to
  provide it
- fixed return value of KIWIImageFormat::createFormat. If no
  format is specified, e.g on xen we need only the format
  configuration, this is just a warning, thus the return
  value of the function should not indicate an error
- use grub2 as bootloader for xen on openSUSE 12.2 JeOS too