##### SUMMARY
win_domain_user always returns changed if a password is specified.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
win_domain_user

##### ANSIBLE VERSION
```paste below
ansible 2.8.1
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/user/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.7.3 (default, Mar 26 2019, 21:43:19) [GCC 8.2.1 20181127]
```

##### CONFIGURATION

##### OS / ENVIRONMENT

ArchLinux

##### STEPS TO REPRODUCE
```yaml
- name: Set AD User Password
      win_domain_user:
        name: '{{ user_name }}'
        password: '{{ password }}'
        state: present
- name: Set AD User Password again
      win_domain_user:
        name: '{{ user_name }}'
        password: '{{ password }}'
        state: present
```

##### EXPECTED RESULTS
The 2nd task to show as not changed.

##### ACTUAL RESULTS
The 2nd task shows as changed, even though the password was already set.
description:
      - Configures the user's street address.
    type: str
  city:
    description:
      - Configures the user's city.
    type: str
  state_province:
    description:
      - Configures the user's state or province.
    type: str
  postal_code:
    description:
      - Configures the user's postal code / zip code.
    type: str
  country:
    description:
      - Configures the user's country code.
      - Note that this is a two-character ISO 3166 code.
    type: str
  path:
    description:
      - Container or OU for the new user; if you do not specify this, the
        user will be placed in the default container for users in the domain.
      - Setting the path is only available when a new user is created;
        if you specify a path on an existing user, the user's path will not
        be updated - you must delete (e.g., C(state=absent)) the user and
        then re-add the user with the appropriate path.
    type: str
  attributes: