Allow development Django versions to be tested with Travis

Author: macro1

.travis.yml

@@ -13,7 +13,7 @@ env:
   - DJANGO="Django>=1.8a,<1.9"
 
 install:
-  - pip install -U coverage coveralls $DJANGO
+  - pip install --pre -U coverage coveralls $DJANGO
   - python -c 'from __future__ import print_function; import django; print("Django " + django.get_version())'
 
 script: coverage run -a setup.py test
@@ -24,6 +24,8 @@ matrix:
      env: DJANGO="Django>=1.6,<1.7"
    - python: 2.6
      env: DJANGO="Django>=1.7,<1.8a"
+   - python: 2.6
+     env: DJANGO="Django>=1.8a,<1.9"
    - python: 3.2
      env: DJANGO="Django>=1.4,<1.5"
    - python: 3.3