Update .gitignore
Update .gitignore

ignoring CMake files.
CognitiveRobotics/object_tracking_2D,CognitiveRobotics/object_tracking_2D,a-price/object_tracking_2D,a-price/object_tracking_2D,CognitiveRobotics/object_tracking_2D,a-price/object_tracking_2D