WIP: Add support for conditionally building with ITKFactoryRegistration

[jcfr]

This commit is NOT ready for integration or review. It depends on #852

This commit introduces option Slicer_USE_ITKFactoryRegistration allowing
to conditionally build with ITKFactoryRegistration. Since latest version
of ITK is expected to address IOFactory issues originally fixed by
introducing ITKFactoryRegistration library, this new option will allow
to easily build Slicer and test that it effectively works without it.

List of SlicerExecutionModel changes:

$ git shortlog 1d3e9a2..edfcb22 --no-merges
Andrey Fedorov (1):
      ENH: add pointer to the wiki documentation

Jean-Christophe Fillion-Robin (1):
      COMP: Add SEMConfigure.h and update config with SlicerExecutionModel_USE_ITKFactoryRegistration