Indigo Demo Mode Update

- Updated camera control in demo mode: Indigo Baxter updates require that no more than 2 cameras be _powered_ at once. The fix for this on the robot dictates that when a camera is closed, it is also powered down, and the other two cameras are powered up. Therefore we need to be careful when the cameras are closed (to prevent killing power to our camera of interest), and close another camera if our camera of interest lacks power. A side effect of this is when a camera is mirrored on the screen, it takes 5 seconds to power up and then open.
- Updated publishers to use queue_size arg
- Updated OpenCV deps to use cv2 and new numpy way of dealing with images
- Fixed Joint Trajectory Action Server (Velocity Mode) spawner: it was continually spawning threads of the JTAS, at which point ROS told the older threads to shut down. This was a rather infinite loop of JTAS spawning