Create one build script for CUDA Toolkit feedstocks

[jakirkham]

Currently every CUDA Toolkit feedstock has a copy of more-or-less the same build.sh and bld.bat scripts. We may benefit by consolidating this logic into centralized build scripts in this repo. That way changes could go into one place and we could avoid drift between feedstocks. It would also make it easier to apply fixes across the CUDA Toolkit feedstocks and maintain consistency in the process.

[carterbox]

This new installer script could fix this issue: conda-forge/cuda-feedstock#52