Return a dict of all available VM images on the cloud provider.

def avail_images(kwargs=None, call=None):
    '''
    Return a dict of all available VM images on the cloud provider.
    '''
    if call == 'action':
        raise SaltCloudSystemExit(
            'The avail_images function must be called with '
            '-f or --function, or with the --list-images option'
        )

    if not isinstance(kwargs, dict):
        kwargs = {}

    if 'owner' in kwargs:
        owner = kwargs['owner']
    else:
        provider = get_configured_provider()

        owner = config.get_cloud_config_value(
            'owner', provider, __opts__, default='amazon'
        )

    ret = {}
    params = {'Action': 'DescribeImages',
              'Owner': owner}
    images = aws.query(params,
                       location=get_location(),
                       provider=get_provider(),
                       opts=__opts__,
                       sigver='4')

    for image in images:
        ret[image['imageId']] = image
    return ret