Add Python 3.4 to supported versions

docs/getting-started/introduction.rst

@@ -39,7 +39,7 @@ What do I need?
 .. sidebar:: Version Requirements
     :subtitle: Celery version 3.0 runs on
 
-    - Python ❨2.5, 2.6, 2.7, 3.2, 3.3❩
+    - Python ❨2.5, 2.6, 2.7, 3.2, 3.3, 3.4❩
     - PyPy ❨1.8, 1.9❩
     - Jython ❨2.5, 2.7❩.