Remove support for py33

Python 3.3 is not supported from Mitaka, as per Infra.
This patch removes the support for the same.

Change-Id: I7cd467af595c5e96df599b16afb83ef59f4d4452

setup.cfg

@@ -16,7 +16,6 @@ classifier =
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.3
     Programming Language :: Python :: 3.4
     Programming Language :: Python :: 3.5