Open Sponsor Logo Slot for Right Keyword

Because we use incomplete keywords, they can be ambiguous.  Eg. there are several keywords called *food*.
 
This change means that keywords are considered in the context of section, which should make the keyword unambiguous.  This is the best current solution while DFP supports R2 and Next Gen.
I could leave them undefined rather than giving them a default value.  That way we know they've been overridden somewhere.  It could save us from the future as well.

(I think I just lazily did this to avoid having to add fixtures to some tests.)