Register a user and session, and then return the session_key and user.

def basic_register(username, password, password2):
    """
    Register a user and session, and then return the session_key and user.
    """
    if password != password2:
        raise InvalidInput(password={'message': "Passwords do not match"},
                           username={'value': username})
    user = User.objects.create_user(username, password)
    return create_session(user.username, password)