update_adzerk: Only update flight data when a campaign is provided.
update_adzerk: Only update flight data when a campaign is provided.

Previously we were updating everything about the campaign,
advertiser, and creative when doing simple actions like pausing a
flight.  This should reduce the cost of updates.

madbook/reddit-plugin-adzerk,madbook/reddit-plugin-adzerk,madbook/reddit-plugin-adzerk