Update hosting services to use HostingServiceHTTPResponse.

Review Request #10217 — Created Oct. 11, 2018 and submitted — Latest diff uploaded

Information

Review Board
release-4.0.x
31a977a...

Reviewers

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.