"Page Author" list excludes users with custom roles

[sudrien]

Scenario: Created new role with Schneider's plugin, restricting new role to only making & editing pages. However, users in this new role were not on the "Page Author" list, so pages could not be transfered to their ownership.

Causes:

1. wp_user_level was not being set in $wpdb->usermeta when these users are created
2. get_editable_user_ids looks for the value in #1 when creating the authors list.

changing

$level_key = $wpdb->prefix . 'user_level';

to

$level_key = $wpdb->prefix . 'capabilities';

showed all users, but doesn't respect levels.

Also, this doesn't pay any heed to page vs. post permissions.

has rotten for long enough