Add flash message when any batch executes successfully.

tailbone/views/batch.py

@@ -583,6 +583,7 @@ class BatchCrud(BaseCrud):
         if self.handler.execute(batch):
             batch.executed = datetime.datetime.utcnow()
             batch.executed_by = self.request.user
+            self.request.session.flash("Batch was executed successfully.")
         return HTTPFound(location=self.view_url(batch.uuid))