Yahoo geocoder throws ugly error to user when you exceed your limits

When you have exceeded your limits to Yahoo, Yahoo sends a poorly formated xml comment that causes php to throw an error:

Warning: simplexml_load_string(): Entity: line 9: parser error : Comment not terminated inCRM_Utils_Geocode_Yahoo::format() (line 127 of /var/aegir/platforms/alberto-ourpowerbase-d7-c4.2/sites/all/modules/civicrm/CRM/Utils/Geocode/Yahoo.php).

I think we should suppress that error by placing an @ in front of the function call. CiviCRM will still catch and log the error, but from the user perspective we silently fail.