made sort keyword optional for grid

edbob/pyramid/grids.py

@@ -185,7 +185,9 @@ def render_grid(request, grid, search=None, **kwargs):
 
 
 def sort_query(query, config, sort_map, join_map={}):
-    field = config['sort']
+    field = config.get('sort')
+    if not field:
+        return query
     joins = config.setdefault('joins', [])
     if field in join_map and field not in joins:
         query = join_map[field](query)