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: I72dd71f8f68b7459593b520ea42e9a8af6aaefba

setup.cfg

@@ -15,7 +15,6 @@ 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

@@ -1,5 +1,5 @@
 [tox]
-envlist = py35,py34,pep8,py27
+envlist = py35,py27,pep8
 
 [testenv]
 usedevelop = True