Fix comment count in parsing Facebook response

[entr]

was getting:

[24-Aug-2016 05:13:23 UTC] PHP Notice:  Undefined property: stdClass::$comments in /var/www/web/app/plugins/EA-Share-Count/includes/class-core.php on line 381
[24-Aug-2016 05:13:23 UTC] PHP Stack trace:
[24-Aug-2016 05:13:23 UTC] PHP   1. shutdown_action_hook() /var/www/web/wp/wp-includes/load.php:0
[24-Aug-2016 05:13:23 UTC] PHP   2. do_action() /var/www/web/wp/wp-includes/load.php:671
[24-Aug-2016 05:13:23 UTC] PHP   3. EA_Share_Count_Core->update_share_counts() /var/www/web/wp/wp-includes/plugin.php:524
[24-Aug-2016 05:13:23 UTC] PHP   4. EA_Share_Count_Core->query_api() /var/www/web/app/plugins/EA-Share-Count/includes/class-core.php:473

[billerickson]

Thanks for this!