Update hosting services to use HostingServiceHTTPResponse.
Review Request #10217 — Created Oct. 11, 2018 and submitted
This is a small update to the hosting service implementations that
switch from the
(data, headers)form of HTTP responses to
HostingServiceHTTPResponse. It's a small step toward modernizing the
hosting services (which would need to come as a series of larger
changes), but gets us closer to a simpler codebase.
Unit tests pass.