Publisher use cases part 1: ad placement

[dmarti]

There is some interest in tracking the implementation of web publisher requirements across a variety of proposals. These requirements range from turning off a particular piece of ad creative on a site to more complex issues such as floor rates by ad vertical.

This issue is a placeholder for an agenda item to introduce a discussion of publisher requirements and to collect links to relevant issues in proposals. This covers in-browser auctions and related placement issues, and a future part 2 will cover reporting issues.

dmarti/in-browser-auction-publisher-issues: Summary and links to web publisher considerations for in-browser ad placements

[dmarti]

Related pull request (already merged) #99