Contributors now get sent to DFP as a param called 'co'

Here's how it works:
when there isn't an author (like a syndicated article from Reuters)
&co=
(like this one: http://www.theguardian.com/world/2014/jul/06/hillary-clinton-angela-merkel-leader)

When there is a single author:
&co=alex-hern
(like this one: http://www.theguardian.com/technology/2014/jul/25/us-congress-banned-editing-wikipedia-trolling)

When there are multiple authors:
&co=angela-monaghan,phillip-inman
(use this as a test: http://www.theguardian.com/business/2014/jul/25/gdp-recession-high-economy-growth-osborne)