Hidden tags aren't sent to the client, so they couldn't be used to
disable ads on topic pages. Do this calculation on the server.
Topic list pages for tags can continue to check on the client because
non-staff get a 404 error when trying to view a hidden tag's topic list.
Enter a list of tags in the new setting no_ads_for_tags to prevent
ads from being rendered on topics with one or more of those tags,
and on topic list pages for those tags.
DFP category targeting param wasn't always being updated on topic
list pages.
Also remove dependency on a category param being passed in to the
component from a template so that we can now place dfp ads
in places that don't have access to the current category and
targeting will still work.
Neil Lalonde
Roman Rizzi
Arpit Jalan