Release version 1.0.0.271

Windows version of NCCL, originally from https://github.com/NVIDIA/nccl and tested on Windows 7 x64.

NOTE: This release requires the nvToolsExt64_1.dll from NVIDIA which is automatically installed in the following directory by the CUDA 8.0 Toolkit: %ProgramFiles%\NVIDIA Corporation\NvToolsExt\bin\x64