Multi-gpu training for YOLO

[1292765944]

It's very cool code for chainercv. By the way, are you going to extend multi-gpu training code for YOLO?

[knorth55]

#596

[apple2373]

Alright, I am still waiting for training script for YOLO.... Well, it's so sad that chainercv do not support any training of YOLO. This issue is for multi-gpu but actually we even can't do single GPU training of YOLO in chainercv (maybe it's in progress in #596 ? ).