Improve CMakeLists Cross-Platform Compatibility for Compilers

[jyoung3131]

Jered notes that we may want to avoid using the explicit calls to CMAKE_C_COMPILER since it conflicts with local default flags.

https://stackoverflow.com/questions/45933732/how-to-specify-a-compiler-in-cmake

• We may want to avoid setting CMAKE_C_COMPILER, CMAKE_CXX_COMPILER, and CMAKE_CUDA_COMPILER in CMakelists.txt
• If we do set CMAKE_C_COMPILER, CMAKE_CXX_COMPILER, and CMAKE_CUDA_COMPILER in CMakelists.txt, we need to do so before any project statements.

[agustin-vaca]

Fixed by PR #145