Kafo

Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1429883

Description of problem:
When you cancel installer right after start for whatever reason, or if it was hardly killed by OOM, it might happen that the satellite.yaml file will get corrupted and eventually the content might be replaced by default content set in Kafo::Configuration::DEFAULT.

Version-Release number of selected component (if applicable):
6.2.7+

How reproducible:
This is very tricky and the installer has to be killed when it is writing into @config_file.

Actual results:
File will be corrupted and the content will be replaced in next run of installer

Expected results:
File will be intacted

Additional info:
I would suggest adding some fail-safe, like transactional write with double buffer, so the original file will not be replaced/rewritten until the write to the new one will be finished.
See method save_configuration(configuration) in Kafo::Configuration where the config save is implemented.