removed django 1.4 and 1.5 from Travis matrix

Author: owais

.travis.yml

@@ -13,8 +13,6 @@ script: "coverage run --source=tests manage.py test"
 after_success:
   coveralls
 env:
-  - DJANGO_VERSION=1.4
-  - DJANGO_VERSION=1.5
   - DJANGO_VERSION=1.6
   - DJANGO_VERSION=1.7
   - DJANGO_VERSION=1.8