fixed a few broken license declarations. should have been BSD not GPL

--HG--
branch : trunk
diff --git a/jinja2/visitor.py b/jinja2/visitor.py
index 8c94803..ad11108 100644
--- a/jinja2/visitor.py
+++ b/jinja2/visitor.py
@@ -6,7 +6,7 @@
     This module implements a visitor for the nodes.
 
     :copyright: Copyright 2008 by Armin Ronacher.
-    :license: GNU GPL.
+    :license: BSD.
 """
 from jinja2.nodes import Node