[0.1.x] User should inherit its parent's Meta.

Otherwise, `ordering` won't be inherited.

Backport of e81d588f551427808bdf54fe7b66b8523bcdf49b from master.
[0.1.x] Call normalize_email on an instance, not a class.

see https://github.com/django/django/pull/1232

Backport of 946f42c9936d0df206b43c98fb15d248a2b09703 from master.