Support ID-based repository URIs, and canonicalize repository URIs

Summary:
Ref T4245. Make `/diffusion/123/` work, but redirect the user to `/diffusion/XYZ/` if the repository has a callsign.

(Right now, every repository has a callsign, so this always redirects.)

Also redirect `/R123:abcdef` if the repository has a callsign.

Also also, move the Pull garbage collector somewhere more sensible.

Test Plan:
  - Added test coverage.
  - Visited `/diffusion/1/`, was redirected.
  - Visited `/diffusion/R1:abcdef`, was redirected.
  - Browsed Diffusion normally.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4245

Differential Revision: https://secure.phabricator.com/D15301

src/applications/diffusion/application/PhabricatorDiffusionApplication.php

@@ -64,7 +64,11 @@ final class PhabricatorDiffusionApplication extends PhabricatorApplication {
           '(?:query/(?P<queryKey>[^/]+)/)?' => 'DiffusionPushLogListController',
           'view/(?P<id>\d+)/' => 'DiffusionPushEventViewController',
         ),
-        '(?P<repositoryCallsign>[A-Z]+)/' => array(
+        '(?:'.
+          '(?P<repositoryCallsign>[A-Z]+)'.
+          '|'.
+          '(?P<repositoryID>[1-9]\d*)'.
+        ')/' => array(
           '' => 'DiffusionRepositoryController',
 
           'repository/(?P<dblob>.*)'    => 'DiffusionRepositoryController',
@@ -115,8 +119,9 @@ final class PhabricatorDiffusionApplication extends PhabricatorApplication {
         // catch-all for serving repositories over HTTP. We must accept
         // requests without the trailing "/" because SVN commands don't
         // necessarily include it.
-        '(?P<repositoryCallsign>[A-Z]+)(?:/.*)?' =>
-          'DiffusionRepositoryDefaultController',
+        '(?:(?P<repositoryCallsign>[A-Z]+)|(?P<repositoryID>[1-9]\d*))'.
+          '(?:/.*)?'
+          => 'DiffusionRepositoryDefaultController',
 
         'inline/' => array(
           'edit/(?P<phid>[^/]+)/' => 'DiffusionInlineCommentController',