datasets.py: Convert image to RGB channel

Converts images with less than 3 channels to RGB. 
Closes #155

utils/datasets.py

@@ -83,7 +83,7 @@ def __getitem__(self, index):
         img_path = self.img_files[index % len(self.img_files)].rstrip()
 
         # Extract image as PyTorch tensor
-        img = transforms.ToTensor()(Image.open(img_path))
+        img = transforms.ToTensor()(Image.open(img_path).convert('RGB'))
 
         # Handle images with less than three channels
         if len(img.shape) != 3: