Drop py34 target and add py35 in tox.ini and setup.cfg

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.

Change-Id: Ie634245d455a8a5a58c09e23b418a10147ca4743
see:https://review.openstack.org/#/c/349069/

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

@@ -1,6 +1,6 @@
 [tox]
 minversion = 1.6
-envlist = py27,pep8,py34
+envlist = py27,pep8,py35
 skipsdist = True
 
 [testenv]
@@ -21,8 +21,8 @@ commands = oslo_debug_helper {posargs}
 basepython = python2.7
 commands = oslo_debug_helper {posargs}
 
-[testenv:debug-py34]
-basepython = python3.4
+[testenv:debug-py35]
+basepython = python3.5
 commands = oslo_debug_helper {posargs}
 
 [testenv:pep8]