Removed older version of python added 3.5

In setup.cfg file the python 3.5 is added
In tox.ini the python 3.5 is added

Change-Id: Ibe5a2e3db791d87cfa3546f9e7b22876c67bf52a

setup.cfg

@@ -16,8 +16,6 @@ classifier =
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.3
-    Programming Language :: Python :: 3.4
     Programming Language :: Python :: 3.5
 
 [files]

tox.ini

@@ -25,16 +25,19 @@ commands =
   stestr run {posargs}
 
 [testenv:pep8]
+basepython = python3
 commands =
     flake8
 # TODO(igordcard): enable pylint on a future patch
 #    pylint --rcfile=.pylintrc --output-format=colorized {posargs:neutron_classifier}
 
 [testenv:dsvm]
+basepython = python3
 setenv = OS_FAIL_ON_MISSING_DEPS=1
          OS_LOG_PATH={env:OS_LOG_PATH:/opt/stack/logs}
 
 [testenv:functional]
+basepython = python3
 setenv = {[testenv]setenv}
          OS_TEST_TIMEOUT=180
          OS_TEST_PATH=./neutron_classifier/tests/functional
@@ -65,18 +68,22 @@ deps =
 commands = stestr run {posargs}
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:cover]
+basepython = python3
 setenv =
   PYTHON=coverage run --source neutron_classifier --parallel-mode
 commands =
   stestr run '{posargs}'
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [flake8]