token regression on mailing labels in 4.4

In 4.4.5 the

{contact.contact_id}

token no longer works in mailing labels

The issue is that if an integer is correctly cast as an integer then the token is ignored. This regression came is as a result of a commit by Coleman labelled fix php warning which add the is_string check. I'm about 95% sure the warning would have been caused by arrays being passed in - in which case & !is_array() might have made sense. In any case I'm satisfied this patch is an improvement & the reason for the regression was over-sight

https://github.com/civicrm/civicrm-core/pull/3474