Diffusion - move some DiffusionRequest queries to occur over Conduit

Summary: Ref T2784. This one was a wee bit complicated. Had to add PhabricatorUser and concept of initFromConduit (or not) to DiffusionRequest.

Test Plan: foreach repo, visited CALLSIGN and clicked a commit and verified they laoded correctly. Hacked code to hit NOT via Conduit and repeated tests to great success.

Reviewers: epriestley

Reviewed By: epriestley

CC: chad, aran, Korvin

Maniphest Tasks: T2784

Differential Revision: https://secure.phabricator.com/D5928

src/applications/diffusion/controller/DiffusionPathCompleteController.php

@@ -27,8 +27,9 @@ final class DiffusionPathCompleteController extends DiffusionController {
 
     $drequest = DiffusionRequest::newFromDictionary(
       array(
-        'repository'  => $repository,
-        'path'        => $query_dir,
+        'user' => $request->getUser(),
+        'repository' => $repository,
+        'path' => $query_dir,
       ));
     $this->setDiffusionRequest($drequest);