New features:
- Release target that checks for both cuda 7.5 and 8 with WITH_CYCLES_CUDA_BINARIES=ON and CYCLES_CUDA_BINARIES_ARCH=sm_20;sm_21;sm_30;sm_35;sm_37;sm_50;sm_52;sm_60;sm_61 options set.
- Option to switch between x86 and x64 builds, the default remains (auto detect the architecture) but can be overridden.
- Option to switch between vs12(2013) and vs14(2015) default is 2013.