Drop testing against Django 1.5

.travis.yml

@@ -18,11 +18,6 @@ env:
     - TOX_ENV=py32-django16
     - TOX_ENV=py27-django16
     - TOX_ENV=py26-django16
-    - TOX_ENV=py34-django15
-    - TOX_ENV=py33-django15
-    - TOX_ENV=py32-django15
-    - TOX_ENV=py27-django15
-    - TOX_ENV=py26-django15
     - TOX_ENV=py27-djangomaster
     - TOX_ENV=py34-djangomaster
     - TOX_ENV=py35-djangomaster

tox.ini

@@ -4,7 +4,7 @@ addopts=--tb=short
 [tox]
 envlist =
        py27-{lint,docs},
-       {py26,py27,py32,py33,py34}-django{15,16},
+       {py26,py27,py32,py33,py34}-django16,
        {py27,py32,py33,py34}-django{17,18},
        {py27,py34,py35}-django{master}
 
@@ -21,7 +21,6 @@ commands = ./runtests.py --fast {posargs} --coverage
 setenv =
        PYTHONDONTWRITEBYTECODE=1
 deps =
-       django15: Django==1.5.6  # Should track minimum supported
        django16: Django==1.6.3  # Should track minimum supported
        django17: Django==1.7.10  # Should track maximum supported
        django18: Django==1.8.4  # Should track maximum supported