Rename HTTPFutureResponseStatus subclasses
Summary: Ref T5655.
Test Plan: Ran arc unit.
Reviewers: Blessed Reviewers, epriestley
Reviewed By: Blessed Reviewers, epriestley
Subscribers: epriestley, Korvin
Maniphest Tasks: T5655
Differential Revision: https://secure.phabricator.com/D10008