modify grab_permission response

Author: tigersk

tigeropen/quote/response/quote_grab_permission_response.py

@@ -18,4 +18,5 @@ def parse_response_content(self, response_content):
         if 'is_success' in response:
             self._is_success = response['is_success']
 
-        self.permissions = string_utils.camel_to_underline_obj(self.data)
+        if self.data:
+            self.permissions = string_utils.camel_to_underline_obj(self.data)