Remove Django 1.7 and add Django 1.9 to the tox test matrix.

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
     coverage-clean
-    py{27,33,34,35}-django{1.7,1.8}
+    py{27,33,34,35}-django{1.8,1.9}
     coverage-report
 
 [testenv]
@@ -16,8 +16,8 @@ commands=
 
 deps =
     -rrequirements/testing-no-django.txt
-    django1.7: django>=1.7,<1.8
     django1.8: django>=1.8,<1.9
+    django1.9: django>=1.9,<1.10
 
 setenv=
     COVERAGE_FILE=.coverage.tox.{envname}