Upgrade testing env name to django18beta

.travis.yml

@@ -21,10 +21,10 @@ env:
     - TOX_ENV=py26-django15
     - TOX_ENV=py27-django14
     - TOX_ENV=py26-django14
-    - TOX_ENV=py34-django18alpha
-    - TOX_ENV=py33-django18alpha
-    - TOX_ENV=py32-django18alpha
-    - TOX_ENV=py27-django18alpha
+    - TOX_ENV=py34-django18beta
+    - TOX_ENV=py33-django18beta
+    - TOX_ENV=py32-django18beta
+    - TOX_ENV=py27-django18beta
 
 install:
   - pip install tox

tox.ini

@@ -3,7 +3,7 @@ envlist =
        py27-{flake8,docs},
        {py26,py27}-django14,
        {py26,py27,py32,py33,py34}-django{15,16},
-       {py27,py32,py33,py34}-django{17,18alpha}
+       {py27,py32,py33,py34}-django{17,18beta}
 
 [testenv]
 commands = ./runtests.py --fast
@@ -14,7 +14,7 @@ deps =
        django15: Django==1.5.6  # Should track minimum supported
        django16: Django==1.6.3  # Should track minimum supported
        django17: Django==1.7.2  # Should track maximum supported
-       django18alpha: https://www.djangoproject.com/download/1.8b1/tarball/
+       django18beta: https://www.djangoproject.com/download/1.8b1/tarball/
        -rrequirements/requirements-testing.txt
        -rrequirements/requirements-optionals.txt