sfml conanfile.py Modification of https://github.com/TyRoXx/conan-sfml by https://github.com/cpbotha to work on Mac

• This uses the tarball instead of the zip file, as Python’s zipfile library does not support symlinks, required on the Mac. See conan-io/conan#336 for more details.
• This also does some extra work to get the SFML dylibs and the included frameworks in the right place.
• Furthermore, it works around the hidden symbol __cpu_model GCC 5 and 6 bug on Ubuntu by patching the SFML linking configuration.

On the Mac, the current conan 0.9.4 sets CMAKE_SKIP_RPATH. If you want these sfml libraries to link correctly with your binary, comment out the CMAKE_SKIP_RPATH in your app’s conanbuildinfo.cmake.

See conan-io/conan#337 for the whole story.