[1.0.X] Fixed #10571 -- Ensured that unicode POST data is correctly encoded by...

[1.0.X] Fixed #10571 -- Ensured that unicode POST data is correctly encoded by the test client. Thanks to Rick Wagner for his help identifying and fixing this problem.

Merge of r10513 from trunk.


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10514 bcc190cf-cafb-0310-a4f2-bffc1f526a37