add Python 3.4 to README

Author: kmike

README.rst

@@ -129,8 +129,8 @@ Make sure `tox`_ is installed and run
 
     $ tox
 
-from the source checkout. Tests should pass under python 2.6, 2.7, 3.2, 3.3
-and PyPy >= 1.9.
+from the source checkout. Tests should pass under python 2.6, 2.7, 3.2, 3.3,
+3.4 and PyPy >= 1.9.
 
 In order to run benchmarks, type