Created by: cjld

add num_classes config to deeplabv3+

Now you can train any number of classes you want:

python3 ./train.py \
    --batch_size=1 \
    --train_crop_size=769 \
    --total_step=50 \
    --num_classes=$NUMBER_YOU_WANT \
    --init_weights_path=$INIT_WEIGHTS_PATH \
    --save_weights_path=$SAVE_WEIGHTS_PATH \
    --dataset_path=$DATASET_PATH