Return Image objects on image.load

In before, image.load returns what Docker API returns, which is
a text stream. This commits propose an improvement for returning
more useful information, which is a list of Image objects being
loaded.
Signed-off-by: Hongbin Lu <hongbin.lu@huawei.com>

docker/models/images.py

@@ -236,13 +236,24 @@ class ImageCollection(Collection):
             data (binary): Image data to be loaded.
 
         Returns:
-            (generator): Progress output as JSON objects
+            (list of :py:class:`Image`): The images.
 
         Raises:
             :py:class:`docker.errors.APIError`
                 If the server returns an error.
         """
-        return self.client.api.load_image(data)
+        resp = self.client.api.load_image(data)
+        images = []
+        for chunk in resp:
+            if 'stream' in chunk:
+                match = re.search(
+                    r'(^Loaded image ID: |^Loaded image: )(.+)$',
+                    chunk['stream']
+                )
+                if match:
+                    image_id = match.group(2)
+                    images.append(image_id)
+        return [self.get(i) for i in images]
 
     def pull(self, name, tag=None, **kwargs):
         """