Summary:
Depends on D19150. Ref T13088. Allow clients to retrieve information about build logs, including log data, over the API.
(To fetch log data, take the `filePHID` to `file.search`, then issue a normal GET against the URI. Use a `Content-Range` header to get part of the log.)
Test Plan: Ran `harbormaster.log.search`, got sensible-looking results.
Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam
Maniphest Tasks: T13088
Differential Revision: https://secure.phabricator.com/D19151