COMP: Resolve deprecation warning for SphinxExamples

CMake Warning at CMake/ITKFactoryRegistration.cmake:230 (message):
  ITK_NO_IO_FACTORY_REGISTER_MANAGER CMake variable is deprecated.  Use
  ITK_NO_IMAGEIO_FACTORY_REGISTER_MANAGER

Resolves: #319

Author: hjmjohnson

src/IO/ImageBase/RegisterIOFactories/CMakeLists.txt

@@ -6,7 +6,7 @@ find_package( ITK REQUIRED )
 # Registering the IO classes manually is usually not necessary,
 # unless this variable is set before calling
 #   "include( ${ITK_USE_FILE} )"
-set( ITK_NO_IO_FACTORY_REGISTER_MANAGER 1 )
+set( ITK_NO_IMAGEIO_FACTORY_REGISTER_MANAGER 1 )
 include( ${ITK_USE_FILE} )
 
 add_executable( RegisterIOFactories Code.cxx )