Merge pull request #26 from sprij/master

Returning multiple sort fields.

Author: akira-dev

flask_rest_jsonapi/querystring.py

@@ -155,7 +155,7 @@ def sorting(self):
                 field = get_model_field(self.schema, field)
                 order = 'desc' if sort_field.startswith('-') else 'asc'
                 sorting_results.append({'field': field, 'order': order})
-                return sorting_results
+            return sorting_results
 
         return []