Make the 'Subscribe' button pop a modal instead.

Summary:
See title.

Also some minor styling/consistency fixes.

Test Plan:
- Clicked subscribe
- Canceled to make sure it went away
- Clicked it again
- Clicked subscribe
- Saw my name in the cc field.

Reviewers: epriestley, chad, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4571

src/applications/differential/controller/DifferentialRevisionViewController.php

@@ -60,7 +60,8 @@ final class DifferentialRevisionViewController extends DifferentialController {
         $repository);
 
     if ($request->getExists('download')) {
-      return $this->buildRawDiffResponse($changesets,
+      return $this->buildRawDiffResponse(
+        $changesets,
         $vs_changesets,
         $vs_map,
         $repository);
@@ -163,8 +164,8 @@ final class DifferentialRevisionViewController extends DifferentialController {
             phutil_render_tag(
               'p',
               array(),
-              pht('This revision has no specified reviewers and needs review.'.
-                  ' You may want to add some reviewers.')
+              pht('This revision has no specified reviewers and needs '.
+                  'review. You may want to add some reviewers.')
             ));
         }
       }
@@ -495,6 +496,7 @@ final class DifferentialRevisionViewController extends DifferentialController {
           'href'    => "/differential/subscribe/{$action}/{$revision_id}/",
           'name'    => $viewer_is_cc ? 'Unsubscribe' : 'Subscribe',
           'instant' => true,
+          'sigil' => 'workflow',
         );
       } else {
         $links[] = array(