Ads: Switch to Bocoup's Revive ad server tag

Adzerk is switching their pricing model and Bocoup is moving away to our own self-hosted [Revive](http://www.revive-adserver.com/) server. This pull request updates the ad tag code to one from the new Revive server. All of the same visual ads are in the rotation. The main difference here is that the ads are no longer served in an `iframe` . Adzerk will be turning off non-enterprise accounts on Sept 5th and will just stop serving ads into the spot so it'd be good to land this before then.