Added support for building SDL sample via cmake, CMake only looks for SDL 1, but by setting SDL_LIBRARY, SDL_INCLUDE_DIR, SDL_IMAGE_LIBRARY, SDL_IMAGE_INCLUDE_DIR manually, SDL2 can be used.  This will need to be patched up to properly support SDL2
Added search for SDL in dependencies directory by default
Added SFML cmake support, only builds the SFML sample related to the version of SFML detected
Fix for GLEW enabled SFML builds
Switched to using FindSFML.cmake from SFML distribution
Added default hint for SFML location in our dependancies directory
Merge pull request #203 from libRocket/feature/cmake-samples

Update cmake to build various samples