rewrite: response.{_get_content(),content}

Steve,

The property

    @property
    request.content

seems to have replaced `request.get_content()`, see https://github.com/django/django/commit/e2b4eddc11b391bc0047032776e9ca7c2f9328b3#diff-8939f1a1c262f654f8dbcecee0e76c73L672

This change makes PS tests pass in Django 1.5. Any feedback on merging it?

I've pinned PS develop (currently on Django 1.3.7) to the current head, so this shouldn't affect the existing site. Do other projects use django-nginx-memcache?

Nick