Remove broken Google Chart

Has been deprecated since 2012 and they've actually removed it over the
last year. Would be nice to replace with something else, but for now
this just removes the broken element.

Fixes #2366

app/views/request_game/play.html.erb

@@ -2,15 +2,12 @@
 
 <div id="game_sidebar" class="game_sidebar">
   <p style="text-align: center">
-    <%= image_tag "https://chart.googleapis.com/chart?chs=250x125&cht=gom&chd=t:#{@percentage}",
-          :size => "250x125",
-          :alt => "A chart showing #{@percentage}% of requests have been categorised",
-          :title => "#{@percentage}% of requests have been categorised" %>
-    <br><%= n_("{{number_of_requests}} request left to categorise / {{total_number_of_requests}} total",
-               "{{number_of_requests}} requests left to categorise / {{total_number_of_requests}} total",
-               @missing,
-               :number_of_requests => number_with_delimiter(@missing),
-               :total_number_of_requests => number_with_delimiter(@total)) %>
+    <br />
+    <%= n_('{{number_of_requests}} request left to categorise / {{total_number_of_requests}} total',
+           '{{number_of_requests}} requests left to categorise / {{total_number_of_requests}} total',
+           @missing,
+           number_of_requests: number_with_delimiter(@missing),
+           total_number_of_requests: number_with_delimiter(@total)) %>
   </p>
 
   <h2><%= _("Top recent players") %></h2>