Redundant error messages on user create

[Dimitri Mazmanov]

Two errors are shown when I skip the password confirmation field upon user creation:
1. Passwords do not match
2. Confirm Password: This field is required

Steps to reproduce
1. Create a new user.
2. Fill in user name, password, but skip the confirm password field.

I should be enough to show one error message: "This field is required"

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/174469

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/174469
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=21d155395cbaa4da50de6453a845c6bdbf0b2773
Submitter: Jenkins
Branch: master

commit 21d155395cbaa4da50de6453a845c6bdbf0b2773
Author: Dimitri Mazmanov <email address hidden>
Date: Thu Apr 16 19:00:47 2015 +0200

    Fix the redundant error message during user create

    Simply check if both password and confirm_password fields are not empty.

    Change-Id: Ie04e0515f15993ed3f693d107475939604e55310
    Closes-Bug: #1445043