Run DF-VO

# Example 1: run default kitti setup
python apis/run.py -d options/kitti/default_configuration.yml

# Example 2: Run custom kitti setup
# kitti_default_configuration.yml and kitti_stereo_0.yml are merged
python apis/run.py -d options/kitti/default_configuration.yml -c options/kitti/kitti_stereo_0.yml