COMP: Fix CMake warning in DGraph project
COMP: Fix CMake warning in DGraph project

This commit fixes the following warning:

  CMake Deprecation Warning at /home/jcfr/Projects/CTK/Utilities/DGraph/CMakeLists.txt:21 (cmake_minimum_required):
    Compatibility with CMake < 2.8.12 will be removed from a future version of
    CMake.

    Update the VERSION argument <min> value or use a ...<max> suffix to tell
    CMake that the project does not need compatibility with older versions.

commontk/CTK,commontk/CTK,commontk/CTK,commontk/CTK