Cavelight audio and updated controller

added Audio source to the cave light prefab and an audio listener to the rover prefab so that you can hear it based on where you are. I'm not sure if the audio is too loud or quiet since I don't know how big the tunnel system is going to be. If it's too loud, just go to the cavelights audio source component and turn it down.
 
I also updated the controller script so that it controls the particle emitters. That way if there's no control buttons being pressed, it will stop emitting particles. It'll take some tweaking to get the particles to look better based on the speed of the rover, but it's at least different enough to tell it's working for now.