BUG: UseHistograms was not getting set on ITK filter

Adding test to verify that the median is not updated.

Change-Id: I8f2999c3bf7c1f5c5417d75fccff65bf52dca9f2
Merge branch 'SIMPLEITK-510_AddUseHistogramsOptionToLabelStatistics' into release

* SIMPLEITK-510_AddUseHistogramsOptionToLabelStatistics:
  BUG: UseHistograms was not getting set on ITK filter

Change-Id: Ifa5a140e1438629b30708a57394eaff2a254b541