Updating django version in py27-1.4

Use newer 1.4 version. Unable to locally reproduce the travis error:

...
  File "/home/travis/build/clouserw/tower/tower/tests/test_l10n.py", line 35, in setup
    tower.activate('xx')
  File "/home/travis/build/clouserw/tower/tower/__init__.py", line 104, in activate
    django_trans._active.value = _activate(locale)
  File "/home/travis/build/clouserw/tower/tower/__init__.py", line 130, in _activate
    t.set_language(locale)
AttributeError: NullTranslations instance has no attribute 'set_language'

Author: jogo

tox.ini

@@ -14,7 +14,7 @@ deps = -egit+https://github.com/jbalogh/[email protected]#egg=jingo
 [testenv:py27-1.4]
 basepython = python2.7
 deps =
-    Django==1.4.10
+    Django==1.4.20
     {[testenv]deps}