Clear Linux* Distro Factory 0.6.0

Image creation was refactored to be more flexible. There is now a 'finalize' step that can be provided via the configuration repository to perform tasks defined by the user on how to properly post-process the files created by 'clr-installer' (e. g. different compressions, further file conversions etc).

Please take a look at the matching release of 'clr-distro-factory-config' for a reference on how to write '-finalize' scripts for your images. Be aware that stdout is used by the process to know what was created by the process so the script is expected to handle output correctly.

Configuration repositories based on previous release would still work with the caveat that the images would no longer be compressed. So attention is required from the user when upgrading to this release.