SUSE/machinery — pull request #192 by dmajda (2014-09-08 13:42:01+00:00)
Title: Remove custom validators mechanism from the SystemDescription class

The custom validators mechanism was unused for many months. Effectively
it is dead code. Now it started complicating one of my refactorings, so
I decided to remove it. If custom validators are ever needed, they can
be trivially restored.