update matrix in .travis.yml

.travis.yml

@@ -2,22 +2,12 @@ language: python
 sudo: false
 python:
   - "2.7"
-  - "3.3"
   - "3.4"
   - "3.5"
 env:
-  - DJANGO=1.7
   - DJANGO=1.8
-  - DJANGO=1.9
+  - DJANGO=1.10
   - DJANGO=master
-matrix:
-  exclude:
-    - python: "3.3"
-      env: DJANGO=1.9
-    - python: "3.3"
-      env: DJANGO=master
-    - python: "3.5"
-      env: DJANGO=1.7
 install:
   - pip install tox coveralls
 script: