Drop py34 target in tox.ini

We support py35 now.We do not have python 3.4 in setup.cfg which declares the explicit
supported versions.so it is no need to keep the supoort for py34.

see:https://review.openstack.org/#/c/349069/

Change-Id: Ic50f8395a9fe727f11aed65b5944b6d45a8be850

.travis.yml

@@ -5,12 +5,10 @@ matrix:
     include:
         - python: 2.7
           env: TOXENV=py27
-        - python: 3.4
-          env: TOXENV=py34
         - python: 3.5
           env: TOXENV=py35
         - env: TOXENV=pep8
 
 install: pip install tox-travis
 
-script: tox
+script: tox

tox.ini

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