[Review] Request from 'aduffeck' @ 'SUSE/machinery/review_141216_improve_analyze_task_spec'

Please review the following changes:
  * b7180f2 Use SystemDescription factory instead of FakeFS + stubs
  * 58c9cd5 Merge pull request #456 from SUSE/update_tracking_bug
  * a33943b Replace tracking bug nummer with correct one