Removed camera close call before every open call.

The SDK currently closes and opens the cameras to reload camera settings, 
which won't work with Indigo Baxter. Cameras that are opened and then
reopened will give the same "settings reload" functionality, so there is no 
need to close a camera before opening it. The unnecessary camera close 
was removed from camera_control.py to prevent toggling power to two
separate cameras before opening the desired camera. See
https://github.com/RethinkRobotics/baxter_interface/pull/43 for more details.