reciprocity/ggrc-core — pull request #675 by SilasX (2013-12-03 00:32:52+00:00)
Title: Fix system parent/slug checking.

Per [story 61722080](https://www.pivotaltracker.com/story/show/61722080), about parent slug (if it is exists) not being checked. Fixed by giving `SystemsConverter` a method `validate_metadata` like other converters.

Also corrected a failing `self.program` lookup to the more general (and implemented) `self.parent_object` call.