profiles: add account upgrade link.

app/presenters/user_presenter.rb

@@ -13,10 +13,6 @@ class UserPresenter
     user.created_at.strftime("%Y-%m-%d")
   end
 
-  def level
-    user.level_string
-  end
-
   def ban_reason
     if user.is_banned?
       "#{user.recent_ban.reason}; expires #{user.recent_ban.expires_at} (#{user.bans.count} bans total)"

app/views/users/_statistics.html.erb

@@ -18,7 +18,12 @@
 
       <tr>
         <th>Level</th>
-        <td><%= presenter.level %></td>
+        <td>
+          <%= user.level_string %>
+          <% if CurrentUser.user == user && !CurrentUser.is_gold? %>
+            (<%= link_to "upgrade", new_user_upgrade_path %>)
+          <% end %>
+        </td>
       </tr>
 
       <tr>