Fix PIL img close warning (#357)

* add scale and ratio params to RandomResizedCrop.get_params

* don't use Image as a context manager to avoid exceptions on close

* flake8

torchvision/datasets/folder.py

@@ -48,7 +48,7 @@ def make_dataset(dir, class_to_idx):
 def pil_loader(path):
     # open path as file to avoid ResourceWarning (https://github.com/python-pillow/Pillow/issues/835)
     with open(path, 'rb') as f:
-        with Image.open(f) as img:
+        img = Image.open(f)
         return img.convert('RGB')