Worked on x-platform issues with CMakeLists.txt, tests, and R scripts.
* Made CMakeList.txt files compatible with CMake 2.6 and 2.8
* Modified CMakeList.txt 'find_program' command for Rscript to work on Linux
* Modified CMakeList.txt 'add_test' command for R scripts to work correctly in the build directory.
* Modified argument in the call to the R scripts to match the new 'add_test'
* Replaced the Windows only 'shell' command in the R scripts with the x-platform 'system2'