WP Add author capabilities to moderate comments to

Author-Capabilities.php

<?php
/* Use this in Functions.php */

function add_publish_caps() {
    // gets the contributor role
    $role = get_role( 'contributor' );

    // Adds capability to moderate comments, edit posts, but not publish posts.  
    // moderate_comments requires edit_posts which is why we need the remove_cap.
    $role->add_cap( 'edit_posts' );
    $role->add_cap( 'moderate_comments' ); 
    $role->remove_cap( 'publish_posts' );
}
add_action( 'admin_init', 'add_publish_caps');

?>