Couple of Diffusion tweaks

Summary:
 - Fix spacing on InfoView inside collasped boxes
 - Fix spacing on stacked PropertyLists in TwoColumn
 - Fix spacing on Readmes on Tablets
 - Fix unset variable on importing commits

Test Plan: Review each of the above cases.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D15496

src/applications/diffusion/controller/DiffusionCommitController.php

@@ -635,6 +635,8 @@ final class DiffusionCommitController extends DiffusionController {
       $author = $author_name;
       $image_uri = null;
       $image_href = null;
+    } else {
+      return null;
     }
 
     $author = phutil_tag('strong', array(), $author);