Close votes automatically after 7 days

Closes #1

views/votes_show_closed.erb

@@ -1,7 +1,13 @@
 <h1><%= @vote.title %></h1>
 
+<% if @vote.expire_on %>
+<p><%= _("Closing date: #{format_date(@vote.expire_on)}") %></p>
+<% end %>
+
 <p><%= @vote.description %></p>
 
+<% if @vote.ratings.length > 0 %>
+
 <h2><%= _("All ratings") %></h2>
 
 <table>
@@ -62,6 +68,14 @@ end
 %>
 <%= bar_chart data, colors: colors, stacked: true, legend: 'bottom' %>
 
+<% else %>
+
+<h2><%= _("Results") %></h2>
+
+<%= _("No results are available because nobody voted on this vote.") %>
+
+<% end %>
+
 <h2><%= _("Organizers") %></h2>
 
 <ul>
@@ -70,7 +84,7 @@ end
   <% end %>
 </ul>
 
-<% if @vote.users.exists?(current_user.id) %>
+<% if @vote.users.exists?(current_user.id) and @vote.expire_on.nil? %>
 
 <h3><%= _("Actions for organizers") %></h3>