Remove broken 'MultiLabelSTAPLEImageFilter'

This commit removes the filter because of the following error:

Traceback (most recent call last):
  File "C:/D/S4R/Slicer-build/lib/Slicer-4.9/qt-scripted-modules/SimpleFilters.py", line 260, in onFilterSelect
    self.filterParameters.create(json)
  File "C:/D/S4R/Slicer-build/lib/Slicer-4.9/qt-scripted-modules/SimpleFilters.py", line 811, in create
    w = self.createIntWidget(member["name"],t)
  File "C:/D/S4R/Slicer-build/lib/Slicer-4.9/qt-scripted-modules/SimpleFilters.py", line 957, in createIntWidget
    w.setValue(int(default))
ValueError: Called setValue(int val) -> void with wrong arguments: (4294967295L,)

Author: jcfr