Update automated tests environments

Author: hawi74

.travis.yml

@@ -5,37 +5,29 @@ python:
   - "2.7"
   - "3.4"
   - "3.5"
+  - "3.6"
+  - "3.7"
 
 env:
-  - DJANGO=1.8
   - DJANGO=1.11
   - DJANGO=2.0
+  - DJANGO=2.1
   - DJANGO=master
 
 matrix:
   fast_finish: true
-  include:
-    - python: "3.6"
-      env: DJANGO=1.11
-    - python: "3.6"
-      env: DJANGO=2.0
-    - python: "3.6"
-      env: DJANGO=master
-    - python: "3.7-dev"
-      env: DJANGO=1.11
-    - python: "3.7-dev"
-      env: DJANGO=2.0
-    - python: "3.7-dev"
-      env: DJANGO=master
   exclude:
+    - python: "2.7"
+      env: DJANGO=2.0
+    - python: "2.7"
+      env: DJANGO=2.1
     - python: "2.7"
       env: DJANGO=master
+    - python: "3.4"
+      env: DJANGO=2.1
     - python: "3.4"
       env: DJANGO=master
-    - python: "2.7"
-      env: DJANGO=2.0
   allow_failures:
-    - python: "3.7-dev"
     - env: DJANGO=master
 
 install: