Upgrade CC-BY 3.0 us to CC-BY 4.0 international

Author: rougier

LICENSE.rst

@@ -3,8 +3,8 @@ License
 
 All code and material is licensed under a 
 
-Creative Commons Attribution 3.0 United States License (CC-by)
+Creative Commons Attribution 4.0 Internatonal License (CC-by)
 
-http://creativecommons.org/licenses/by/3.0/us
+http://creativecommons.org/licenses/by/4.0/
 
 See the AUTHORS.rst file for a list of contributors.