Added service to update video parameters and caught exception in case of incorrect parameter file

This was causing a limited FPS at boot-up on the kingfisher, probably because ROS_HOME was not correct and the default name for the camera info could not be found.

Missing the file is now reported but does not prevent video acquisition. 

Also the streaming function a printing any exception, but roslaunch kept hiding the output. The exceptions are now caught and sent to logerror.