View: Correctly count the length of the view using self._rows

self._total_rows contained total amount of rows in a view. Use
len(self._rows) to determine the correct length of the result.

trombi/client.py

@@ -526,7 +526,7 @@ def __init__(self, result):
         self._rows = result['rows']
 
     def __len__(self):
-        return self._total_rows
+        return len(self._rows)
 
     def __iter__(self):
         return iter(self._rows)