Reorganized Assets folder.
Added sprite sheet for Ruff.
Added Physics Editor definition for Ruff Attack One.
Added trivial code in HelloWorld to get Ruff on the screen. Loads sprite sheet into the cache, then creates a CCPhysicalSprite (box2d) using 1st sprite frame of attack one animation.
TODO: Instead of connecting Ruff sprite to sample box body, use the Physics Editor "ruff-attack-one" body we've created instead.