Allow closing accounts

Closes #37

views/admin.erb

@@ -7,15 +7,17 @@
     <tr>
       <th><%= _("Email") %></th>
       <th><%= _("Created") %></th>
+      <th><%= _("Closed") %></th>
       <th><%= _("Admin") %></th>
       <th><%= _("Votes") %></th>
       <th><%= _("Ratings") %></th>
     </tr>
   </thead>
-  <% @users.sort_by { |user| user.email }.each do |user| %>
+  <% all_users.each do |user| %>
     <tr>
       <td><a href="/users/<%= user.id %>"><%= user.email %></a></td>
       <td><%= format_date(user.created_at) %></td>
+      <td><%= active(user) ? nil : format_date(user.closed_at) %></td>
       <td><%= user.admin %></td>
       <td><%= user.votes.length %></td>
       <td><%= user.ratings.length %></td>