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/drupalorg-2015.md

@@ -7,12 +7,14 @@ speakerdeck:
   ratio: "1.77777777777778"
   url: https://speakerdeck.com/opdavies/drupal-dot-org-in-14
 events:
-  - name: DrupalCamp Brighton
-    location: Brighton, UK
-    date: 2015-01-18
-  - name: DrupalCamp London 2015
+  -
+    name: DrupalCamp London 2015
     location: London, UK
     date: 2015-02-28
+  -
+    name: DrupalCamp Brighton
+    location: Brighton, UK
+    date: 2015-01-18
 ---
 
 A retrospective of the Drupal Association’s work in 2014 and a look forward to what we’ll be working on in 2015.