Update contactcreator.php

Error in contacts created by plugin "Contact Creator"
See the related tracker on
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33605
This pull request corects this one:
https://github.com/joomla/joomla-cms/pull/3433#issuecomment-40301384

source: www.allaroundtheweb.it/segui-blog-allaroundtheweb/categoria/joomla/articolo/382/joomla-3-exception-with-message-contact-not-found-come-risolvere-questo-baco-fastidioso-how-to-resolve.html