Train from --data path/to/dataset.zip feature (#4185)

* Train from `--data path/to/dataset.zip` feature

* Update dataset_stats()

* cleanup

* cleanup2

models/experimental.py

@@ -5,7 +5,7 @@ import torch
 import torch.nn as nn
 
 from models.common import Conv, DWConv
-from utils.google_utils import attempt_download
+from utils.downloads import attempt_download
 
 
 class CrossConv(nn.Module):