Ignoring requests containing list instead of dict

If a request's body is a json list instead of a json object django-oauth-toolkit raises and exception. It breaks bulk requests for drf for example. This commit fixes it.

Author: sassanh

oauth2_provider/oauth2_backends.py

@@ -180,7 +180,7 @@ def extract_body(self, request):
         """
         try:
             body = json.loads(request.body.decode("utf-8")).items()
-        except ValueError:
+        except AttributeError, ValueError:
             body = ""
 
         return body