yolov5_simplify

Thx for the origin YOLOv5 project from: https://github.com/ultralytics/yolov5

This project is just the simpliication of the yolov5 with:

1. Only support Pytorch
2. Only contain inference but not training stage
3. No additional operations support (eg. save results, visualize features, ...)
4. Weights can be downloaded from https://github.com/ultralytics/yolov5/releases