Display committed date in Revision Status field

Summary:
This is slightly more complicated for this reason:

- We don't set `dateCommitted` for normal commits, only for markcommitted.
-- We need to add this date to old revisions now.

Test Plan:
Reparse a revision - commit date was set.
Conduit `markcommitted` - commit date was set.
Run SQL script.
Display closed revision.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Koolvin

Differential Revision: https://secure.phabricator.com/D2282

resources/sql/patches/135.datecommitted.sql

@@ -0,0 +1,7 @@
+UPDATE phabricator_differential.differential_revision SET
+  dateCommitted = (
+    SELECT MIN(dateCreated)
+    FROM phabricator_differential.differential_comment
+    WHERE revisionID = differential_revision.id AND action = 'commit'
+  )
+  WHERE status = 3 AND dateCommitted IS NULL;