Add Python 3.5 classifier and venv

Now that is a passing gate job,we can claim support for
Python 3.5 in the classifier,This patch also adds the
convenience py35 venv.

Change-Id: I2b786d51ce4f276d465f7b12b5da53aa7df64287

setup.cfg

@@ -17,6 +17,7 @@ classifier =
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.4
+    Programming Language :: Python :: 3.5
 
 [files]
 packages =