BUG: Revert "BUG: ExtensionBuildSystem: Fix ExperimentalUpload on VS2013"

This reverts commit 4f45e6c05f14335a0d4c19f64b6f172bb43cb387.

It caused build errors in extensions, such as SlicerRT:

CMake Error at C:/D/N/Slicer-0-build/Slicer-build/SlicerConfig.cmake:96 (message):
To be effective, 'find_package(Slicer COMPONENTS ConfigurePrerequisites)'
should be placed before any calls to 'project()' or
'enable_language()'.Before re-configuring, make sure to clean the build
directory: C:/D/N/E-0/SlicerRT-build
Call Stack (most recent call first):
CMakeLists.txt:24 (find_package)

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25572 3bd1e089-480b-0410-8dfb-8563597acbee