Migrate repositories to use Passphrase for credential management

Summary: Fixes T4122. Ref T2230. Instead of storing credentials on each repository, store them in Passphrase. This allows easy creation/management of many repositories which share credentials.

Test Plan:
  - Upgraded repositories.
  - Created and edited repositories.
  - Pulled HTTP and SSH repositories.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2230, T4122

Differential Revision: https://secure.phabricator.com/D7629

src/applications/diffusion/controller/DiffusionRepositoryEditMainController.php

@@ -481,6 +481,14 @@ final class DiffusionRepositoryEditMainController
       pht('Remote URI'),
       $repository->getHumanReadableDetail('remote-uri'));
 
+    $credential_phid = $repository->getCredentialPHID();
+    if ($credential_phid) {
+      $this->loadHandles(array($credential_phid));
+      $view->addProperty(
+        pht('Credential'),
+        $this->getHandle($credential_phid)->renderLink());
+    }
+
     return $view;
   }