Cleanup of all existing cmake_minimum_required statements.

1) moved them to the very top of the project.
2) different files had different mimimums, harmonized them all
to the greatest, 2.8.9.

This fixes CMake 3.0rc1 warnings like:

 CMake Warning (dev) at Utilities/gdcmzlib/CMakeLists.txt:9 (cmake_minimum_required):
   Compatibility with CMake < 2.4 is not supported by CMake >= 3.0.
Merge branch 'release'
FIX: another possible sort crash
COMP: fix for build directory names containing blanks
Merge branch 'release'