Changed CMakeList to support both OS X and Linux tests

ctest -R analysis_module -E python
Test project /ert/build
    Start 143: analysis_module_test_RML
1/4 Test #143: analysis_module_test_RML .........   Passed    0.00 sec
    Start 144: analysis_module_test_RMLI
2/4 Test #144: analysis_module_test_RMLI ........   Passed    0.00 sec
    Start 145: analysis_module_rml
3/4 Test #145: analysis_module_rml ..............   Passed    0.00 sec
    Start 146: analysis_module_rmli
4/4 Test #146: analysis_module_rmli .............   Passed    0.00 sec