Carla does not detect traffic lights

[subhash]

Steps to reproduce

1. Extract traffic light images from rosbag. To do this, create a dir called image_dump under tl_detector and run rosbag play <bag>. This will send image messages to /image_raw/ topic which is captured by function capture_image_cb. Check tl_detector.py and change code as necessary
2. Run detection on these images to see if traffic lights are detected correctly. Site model is site_frozen_inference_graph.pb. Use commented out code of object_detection.utils to mark on image. Check tl_classifier.py for details