Consistent ordering and formatting for talk events

Use a consistent format for talk events, with the most recent talk at
the top of the list with the rest in a descending order.

This removes the need to use a `reverse` filter in the events partial.

source/_talks/getting-your-data-into-drupal-8.md

@@ -20,15 +20,16 @@ meta:
       height: 1440
       type: image/png
 events:
-  - name: Drupal Bristol
-    date: 2017-01-18
-    location: Bristol, UK
-    url: https://www.drupalbristol.org.uk
-
-  - name: DrupalCamp London 2017
+  -
+    name: DrupalCamp London 2017
     date: 2017-03-04
     time: "12:05 - 12:50"
     location: London, UK
+  -
+    name: Drupal Bristol
+    date: 2017-01-18
+    location: Bristol, UK
+    url: https://www.drupalbristol.org.uk
 ---
 
 If you’ve moved a site from Drupal 6 to 7, the chances are that you’ve either used the upgrade path to update your old site in-place, or you built a new site from scratch and used the Migrate module from contrib to migrate your data from the old database.