Added scenes.image

This is a temporary solution for not working voice commands as mentioned here https://github.com/wango911/TF2-Gamemode-GMod13/issues/2. It must placed into garrysmod\scenes replacing the original file (add instructions to README). Temporary, because it'll still get replaced again if an update is released or you verify game cache.
We have to ask Garry to include TF2 scenes with Gmod.