Convert all modeltests to use absolute imports, rather than relative ones.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16975 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/basic/models.py

@@ -6,6 +6,7 @@ This is a basic model with only two non-primary-key fields.
 """
 from django.db import models
 
+
 class Article(models.Model):
     headline = models.CharField(max_length=100, default='Default headline')
     pub_date = models.DateTimeField()