use icons from icon font

app/views/roles/index.html.erb

@@ -34,7 +34,7 @@ See doc/COPYRIGHT.rdoc for more details.
           <%= content_tag(role.builtin? ? 'em' : 'span', link_to(role.name, :action => 'edit', :id => role)) %>
         </td>
         <td align="center" style="width:15%;">
-          <%= image_tag('webalys/check.png', :alt => l(:general_text_Yes)) if role.is_a?(GlobalRole) %>
+          <%= icon_wrapper('icon-context icon-yes', I18n.t(:general_text_Yes)) if role.is_a?(GlobalRole) %>
         </td>
         <td align="center" style="width:15%;">
           <% unless role.builtin? %>