Always display Branch in revision

Summary:
I, as an author, sometimes forget branch associated with a revision.
Plus setting ##differential.show-host-field## makes a false sense of security
that branch will stay hidden so that I can name it
//finally_solve_this_crap_which_makes_no_sense//. But it is published in
Accepted and Request Changes e-mails anyway.

Test Plan: Display revision with disabled ##differential.show-host-field##.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1602

conf/default.conf.php

@@ -597,8 +597,8 @@ return array(
 
   'differential.field-selector' => 'DifferentialDefaultFieldSelector',
 
-  // Differential can show "Host", "Path" and "Branch" fields on revisions, with
-  // information about the machine, working directory and branch where the
+  // Differential can show "Host" and "Path" fields on revisions, with
+  // information about the machine and working directory where the
   // change came from. These fields are disabled by default because they may
   // occasionally have sensitive information; you can set this to true to
   // enable them.

src/applications/differential/field/selector/default/DifferentialDefaultFieldSelector.php

@@ -42,13 +42,13 @@ final class DifferentialDefaultFieldSelector
         array(
           new DifferentialHostFieldSpecification(),
           new DifferentialPathFieldSpecification(),
-          new DifferentialBranchFieldSpecification(),
         ));
     }
 
     $fields = array_merge(
       $fields,
       array(
+        new DifferentialBranchFieldSpecification(),
         new DifferentialArcanistProjectFieldSpecification(),
         new DifferentialApplyPatchFieldSpecification(),
         new DifferentialRevisionIDFieldSpecification(),