exclude 2.x Python with 2.x Django

Author: igorkramaric

.travis.yml

@@ -15,6 +15,12 @@ env:
     - DJANGO=1.11
     - DJANGO=2.0
     - DJANGO=2.1
+matrix:
+  exclude:
+    - python: "2.7"
+      env: DJANGO=2.0
+    - python: "2.7"
+      env: DJANGO=2.1
 install:
   - pip install django==${DJANGO} Pillow psycopg2
   - pip install .