NGIN-13: The OpenRTB 2.2 spec says that VAST must be returned in the bid response adm as XML or that it must be returned from the Win Notice URL (nurl) : "nurl":"http://adserver.com/WinNoticeUrlThatReturnsVAST". Also the OpenRTB 2.2 spec suggests that the adm markup contents should be rawurlencoded(), so that change was made as well.