add a travis test against django 1.10

Author: thraxil

.travis.yml

@@ -6,6 +6,7 @@ python:
 env:
   - DJANGO="Django>=1.8.0,<1.9.0"
   - DJANGO="Django>=1.9.0,<1.10.0"
+  - DJANGO="Django>=1.10,<1.11.0"
 
 # command to install dependencies
 install: