Remove support for py34

The gating on python 3.4 is restricted to <= Mitaka. This is due to
the change from Ubuntu Trusty to Xenial, where only python3.5 is
available. There is no need to continue to keep these settings.

Change-Id: I4373f5ee1a7addfe981818ef059c73a57594d624

setup.cfg

@@ -17,7 +17,6 @@ classifier =
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.4
     Programming Language :: Python :: 3.5
 
 [files]

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = pep8,py35,py34,py27,docs
+envlist = py35,py27,pep8,docs
 skipsdist = True
 
 [testenv]