Updating tests to run against latest Django versions (1.4.10/1.5.5/1.6)

Removed 1.2 since usage for that is very low. Updated 1.4/1.5 to the latest point release and added tests for 1.6

.travis.yml

@@ -2,17 +2,17 @@ language: python
 python:
   - "2.7"
 env:
-  - DJANGO_VERSION=1.2.7
-  - DJANGO_VERSION=1.3.1
-  - DJANGO_VERSION=1.4
-  - DJANGO_VERSION=1.5.1
+  - DJANGO_VERSION=1.3.7
+  - DJANGO_VERSION=1.4.10
+  - DJANGO_VERSION=1.5.5
+  - DJANGO_VERSION=1.6
 matrix:
   include:
     - python: 3.3
-      env: DJANGO_VERSION=1.5.1
+      env: DJANGO_VERSION=1.6
   allow_failures:
     - python: 3.3
-      env: DJANGO_VERSION=1.5.1
+      env: DJANGO_VERSION=1.6
 before_install:
   - sudo apt-get update && sudo apt-get build-dep python-imaging
 install: