get_avatar custom image classes

[tigusigalpa]

Hi, guys!
I just think we need to allow add a new classes to image returned by get_avatar() function at /wp-includes/pluggable.php. So my solution is to add something like

do_action('custom_avatar_class');

so the final code is:

$avatar = "<img alt='{$safe_alt}' src='{$out}' class='avatar avatar-{$size} photo";
do_action('custom_avatar_class');
$avatar .= "' height='{$size}' width='{$size}' />";

I think it will helps for theme developers to customize avatar image.

[tigusigalpa]

Or we can add new filter for avatar classes, i think it will be more productive)

[SergeyBiryukov]

Duplicate of #27336.