COMP: Update SlicerExecutionModel to fix issue with find_package(ITK)

Associated issues:
  https://issues.itk.org/jira/browse/ITK-3294
  https://github.com/Slicer/SlicerExecutionModel/issues/35

Thanks to "Hans Johnson <hans-johnson@uiowa.edu>" for tracking down
and identifying the problem and thanks to "Matt McCormick <matt.mccormick@kitware.com>"
for submitting a fix.

//---------------
$ git shortlog 4e61f6..feef59e --no-merges
Matt McCormick (1):
      BUG: Allow projects to specify their own list of ITK COMPONENTS. #35
//---------------

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23471 3bd1e089-480b-0410-8dfb-8563597acbee