Dashboard avatars: No need to load 40px images if we render them in 24px

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/views/events/_event.html.haml

@@ -4,7 +4,7 @@
       #{time_ago_in_words(event.created_at)} ago.
 
     = cache event do
-      = image_tag avatar_icon(event.author_email), class: "avatar s24", alt:''
+      = image_tag avatar_icon(event.author_email, 24), class: "avatar s24", alt:''
 
       - if event.push?
         = render "events/event/push", event: event