Test against Django 1.9 by default

All tests are executed against Django 1.9, with 1.7 and 1.8 only basic
test with SQLite is executed.
Signed-off-by: Michal Čihař <michal@cihar.com>

.travis.yml

@@ -14,14 +14,15 @@ python:
 # build matrix configuration
 env:
   matrix:
-    - CI_PIP_DEPS="Django>=1.8,<1.9" CI_MODE=lint
-    - CI_PIP_DEPS="Django>=1.8,<1.9" CI_MODE=setup
-    - CI_PIP_DEPS="Django>=1.8,<1.9" CI_DATABASE=mysql
-    - CI_PIP_DEPS="Django>=1.8,<1.9" CI_DATABASE=postgresql
+    - CI_PIP_DEPS="Django>=1.9,<1.10" CI_MODE=lint
+    - CI_PIP_DEPS="Django>=1.9,<1.10" CI_MODE=setup
+    - CI_PIP_DEPS="Django>=1.9,<1.10" CI_DATABASE=mysql
+    - CI_PIP_DEPS="Django>=1.9,<1.10" CI_DATABASE=postgresql
     - CI_PIP_DEPS="Django>=1.7,<1.8"
     - CI_PIP_DEPS="Django>=1.8,<1.9"
+    - CI_PIP_DEPS="Django>=1.9,<1.10"
     - CI_PIP_DEPS="--pre django"
-    - CI_PIP_DEPS="Django>=1.8,<1.9" CI_DATABASE=postgresql CI_MODE=selenium
+    - CI_PIP_DEPS="Django>=1.9,<1.10" CI_DATABASE=postgresql CI_MODE=selenium
   global:
     - DJANGO_SETTINGS_MODULE=weblate.settings_test
     - CI_REQUIREMENTS=travis