Provide vertical margins around login buttons

Summary: Ref T1536. If you only have button-based logins, the new login screen looks weird.

Test Plan:
Before

{F46725}

After

{F46726}

Reviewers: chad, jamesr

Reviewed By: chad

CC: aran

Maniphest Tasks: T1536

Differential Revision: https://secure.phabricator.com/D6225

src/__celerity_resource_map__.php

@@ -923,7 +923,7 @@ celerity_register_resource_map(array(
   ),
   'auth-css' =>
   array(
-    'uri' => '/res/911e97cb/rsrc/css/application/auth/auth.css',
+    'uri' => '/res/751cacaa/rsrc/css/application/auth/auth.css',
     'type' => 'css',
     'requires' =>
     array(

webroot/rsrc/css/application/auth/auth.css

@@ -4,7 +4,7 @@
 
 .phabricator-login-buttons {
   max-width: 508px;
-  margin: auto;
+  margin: 16px auto;
 }
 
 .phabricator-login-buttons .phabricator-login-button .button {