[BZ 1032033] - Sort unavailable & alerted resources portlet - parent first
Fix a few issues with the prior commit for this issue (e429846dd715e0)
- needed to be able to handle null ancestry (for platforms, which can
  be problem resources like anything else). This fix fixed the test
  failures as well.
- Restore the previous ProblemResourceComposite constructor since this
  class *is* exposed remotely.  Add new entry for new constructor.