Support slightly prettier repository URIs in Diffusion

Summary: Fixes T4245. When a repository has a short name, use `/source/shortname/` as its primary URI.

Test Plan:
  - Cloned Git repositories from shortnames via HTTP and SSH.
  - Cloned Mercurial repositories from shortnames via HTTP and SSH.
  - Cloned Subversion repositories from shortnames via SSH.
  - Browsed Git, Mercurial and Subversion repositories.
  - Added and removed short names to various repositories.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4245

Differential Revision: https://secure.phabricator.com/D16851

src/applications/diffusion/controller/DiffusionLastModifiedController.php

@@ -16,6 +16,7 @@ final class DiffusionLastModifiedController extends DiffusionController {
     $drequest = $this->getDiffusionRequest();
 
     $paths = $request->getStr('paths');
+
     try {
       $paths = phutil_json_decode($paths);
     } catch (PhutilJSONParserException $ex) {