List all DRAC users

    CLI Example:

    .. code-block:: bash

        salt dell dracr.list_users

def list_users(host=None,
               admin_username=None,
               admin_password=None,
               module=None):
    '''
    List all DRAC users

    CLI Example:

    .. code-block:: bash

        salt dell dracr.list_users
    '''
    users = {}
    _username = ''

    for idx in range(1, 17):
        cmd = __execute_ret('getconfig -g '
                            'cfgUserAdmin -i {0}'.format(idx),
                            host=host, admin_username=admin_username,
                            admin_password=admin_password)

        if cmd['retcode'] != 0:
            log.warning('racadm returned an exit code of %s', cmd['retcode'])

        for user in cmd['stdout'].splitlines():
            if not user.startswith('cfg'):
                continue

            (key, val) = user.split('=')

            if key.startswith('cfgUserAdminUserName'):
                _username = val.strip()

                if val:
                    users[_username] = {'index': idx}
                else:
                    break
            else:
                if _username:
                    users[_username].update({key: val})

    return users