Add missing trailing slashes to crumb links in Diffusion

Summary:
In most cases this just makes the URIs more consistent, but it's funky/breakish for SVN repositories which are only partially tracked.

See also T3915, and IRC.

Test Plan:
  - Browsed some repositories, verified URIs generated as expected, with trailing slashes for directories.
  - Verified nothing goofy happened in the extremes (like double slashes on the first crumb).

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D7209

src/applications/diffusion/controller/DiffusionController.php

@@ -192,7 +192,7 @@ abstract class DiffusionController extends PhabricatorController {
               'href' => $drequest->generateURI(
                 array(
                   'action' => $action,
-                  'path' => $accum,
+                  'path' => $accum.'/',
                 )),
             ),
             $part.'/');