Restrict data shown on the user page

Coordinator:

Admin:

Closes #398

app/views/admin/users/show/_course_participations.html.erb

@@ -15,9 +15,11 @@
     <tbody>
 
       <% @user.course_participations.each do |cp| %>
-        <%= table_row_link_to_if_rights cp, admin_course_participation_url(cp) do %>
-          <td><%= cp.course_edition.name_with_code %></td>
-          <td><%= course_participation_status_tag cp %></td>
+        <% if can? :show, cp %>
+          <%= table_row_link_to admin_course_participation_url(cp) do %>
+            <td><%= cp.course_edition.name_with_code %></td>
+            <td><%= course_participation_status_tag cp %></td>
+          <% end %>
         <% end %>
       <% end %>