Raise min required django version to 1.4.2

Has a some nice helpers for 2 to 3 transition, namely, django.utils.six

.travis.yml

@@ -6,14 +6,14 @@ python:
 env:
   - DJANGO='https://github.com/django/django/tarball/stable/1.5.x' DB='postgres'
   - DJANGO='https://github.com/django/django/tarball/stable/1.5.x' DB='sqlite'
-  - DJANGO='django>=1.4,<1.5' DB='postgres'
-  - DJANGO='django>=1.4,<1.5' DB='sqlite'
+  - DJANGO='django>=1.4.2,<1.5' DB='postgres'
+  - DJANGO='django>=1.4.2,<1.5' DB='sqlite'
 matrix:
   exclude: # python 3 support only for django>=1.5
     - python: 3.2
-      env: DJANGO='django>=1.4,<1.5' DB='postgres'
+      env: DJANGO='django>=1.4.2,<1.5' DB='postgres'
     - python: 3.2
-      env: DJANGO='django>=1.4,<1.5' DB='sqlite'
+      env: DJANGO='django>=1.4.2,<1.5' DB='sqlite'
 before_install:
   - export PIP_USE_MIRRORS=true
 install:

setup.py

@@ -35,7 +35,7 @@ def find_version(*file_paths):
     packages=[
         'timezone_field',
     ],
-    install_requires=['django', 'pytz'],
+    install_requires=['django>=1.4.2', 'pytz'],
     classifiers=[
         'Development Status :: 4 - Beta',
         'Environment :: Web Environment',