Replace python version for tox
Replace python version for tox

Basepython version changed from python3.4 up to python3.5 for tox.

Change-Id: I87d38eb710731c7ecf6cfde90cf1609e495996dc

openstack/freezer-web-ui,openstack/freezer-web-ui,openstack/freezer-web-ui,openstack/freezer-web-ui