ENH: Simplify logic for pushing sitk objects to slicer

After reviewing the SimpleFilters code a simpler and
more robust methods of pushing SimpleITK images to
slicer was identified.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23258 3bd1e089-480b-0410-8dfb-8563597acbee