Refactor i18n so that all community information is available

This makes it easier to use non-chapter communities on the site in future.

app/views/site/communities.html.erb

@@ -9,7 +9,7 @@
 <p><%= t ".local_chapters.list_text" %></p>
 <ul>
   <% @local_chapters.each do |chapter| %>
-    <li><a href="<%= chapter.url %>"><%= t "osm_community_index.local_chapter.#{chapter.id}.name" %></a></li>
+    <li><a href="<%= chapter.url %>"><%= t "osm_community_index.communities.#{chapter.id}.name" %></a></li>
   <% end %>
 </ul>