0.0.0.201401171228: Remove SFML Source
Removed included source of SFML. Linking SFML library now relies
on the find_package() CMake function and the findSFML.cmake file
included with SFML. This keeps the Pong source tree lightweight and
is consistent with how SFML was designed to be used. Adapts more
easily to the client operating system.
0.0.0.201401171237: Find SFML should now work on Mac OS X.