Feature/capture image

It is now possible to capture an image when firing (by sending the appropriate command to the python video server). Nothing is done with the image yet.
I'll side with Damien on this one. In my opinion, there is a very limited set of instructions the game server could want to send to the video server which does not justify adding a layer.
Let's just keep this piece of code centralized in a few methods and it will be easy to implement protobuff if needed later.